Since this thread is now the "MadVR discussion" thread, here is my view on it all.
First and foremost, for anyone who is reading these posts and thinking "This sounds like a great addition to my new JVC", keep these things in mind:
MadVR ONLY works with ripped content (i.e. computer files). I have heard you can play a blu ray off an internal drive as well, but I am not sure on that. It definitely doesn't work with Netflix, Amazon, Hulu, or any other streaming service that delivers 4k UHD. Nor will it work to upscale your PSVue, Cable TV, Satellite TV, or any other external source. This makes it an "accessory for watching blu rays". And this is basically what the Panasonic 820 and 9000 do, only they can also do a hobbled version of Netflix and Amazon and can't do files or a slick front end like Kodi. MadVR can do it better than Panasonic, but at the cost of an HTPC and a lot of setup.
So here is the "TL/DR" of my long post:
If you are like me and watch a lot of 4k streamed content, you will be using the JVC's internal tone mapping for ALL this content, not just the stuff you have ripped into files. It doesn't make much sense to add another tone mapping device for a small percentage of content unless it was super cheap and super easy to do without complicating your setup.
For me, Blu Rays are ~50% of my theater viewing, with UHD blu rays maybe twice a month, so perhaps 3% of my TOTAL viewing. For the other 50%, about 30% of that is UHD content from streamed sources that MadVR can't work with. So MadVR would get me better tone mapping on 3% of my viewing, and better upscaling on ~47% of my content.
The JVC already tone maps just fine for a lot of content, and it sounds like MadVR really only outshines significantly on some content. So of the 3% of UHD discs I watch, even if half are improved, this is only 1.5% of my total viewing being improved. That's a tough sell.
For the other ripped content (~47% of total viewing), I have doubts that the improvement in upscaling is significant enough to warrant the cost, but even if it was, there are other factors. I have a super simple system right now, with one source and 100% of my media available on that one source. I would lose this, and lose the simplicity of my system, as well as the uniformity of that system in other rooms of the house. I would have to abandon Plex in the theater for Kodi, and I would have to move half my content to a separate source, meaning I would only see half of my content at any one time. It is just too far of a step backwards for me to justify the cost.
All that being said, if I could get even an incremental increase in quality by just adding an HTPC and some free software, I would still do it, as long as I don't sacrifice anything I already have. That won't happen until MadVR works like a Lumagen (or like the internal features of the JVC) with just a simple in and out HDMI setup. When (or if) it ever happens, I will be the first in line to add it to my rack. Until then, it is just an accessory that would be a big step backwards for an incremental improvement in a small percentage of my viewing.
Now for the long version with details: (If you don't like long posts, just skip the rest)
I believe I am the perfect candidate for MadVR in some respects. I already have a pretty in depth file based media system. I run a PC based Plex server in my rack sporting an Intel i7-8700 cpu, 16gb ram, and 64 terabytes of hard drive space in 4 raid arrays. It is connected to my enterprise level network with 10gbe ethernet cables and switches, allowing me to rip content remotely from my office/gaming computer and send it to the Plex storage at ~300 Megabytes per second (about 3x faster than over a regular network, which is a big deal when moving 30-100 gigabytes at a time). And it is connected to the internet via fiber optic with 1000/1000mbps speed, meaning I can stream direct (no transcoding) over internet reliably as long as I have decent internet wherever I am. The cpu in this server can transcode 5 streams at once and still be able to send direct streams to all my TV's at once (tested 5 transcodes and 3 direct streams at once). I have around 900 blu rays ripped, and 80 4k uhd blu rays, as well as hundreds of TV episodes I recorded from HDHomeRun and removed commercials from. This wasn't a cheap setup, but it performs flawlessly 99.5% of the time.
Despite having all this content on file, I still won't be using MadVR (at this time)
Why? It would be a huge step backwards for me in every other way.
As I said above, I use my Plex server in the theater for about 50% of the content I watch in there. Of that, very little is 4k UHD (yet). I used to use Kodi, but file management was a pain, it took hours to get set right on the theater, then I had to repeat for all the other TV's in my house. Plex is a server, and the app is available on almost all devices. When streaming direct the quality is as good as off a blu ray, but when your media device can't handle it, it will transcode automatically and "just work". MadVR wouldn't work with this setup, so now I would be back to installing Kodi and having a different source to select to. Granted, with the Plex backend I could simplify a Kodi install, but Kodi doesn't get me anything I don't already have, and I lose some things like watching local TV (i.e. sports) that I get with Plex.
The other 50% of the time in my theater, I am watching Netflix or Amazon, and sometimes PSVue, HBONow, or ShowtimeAnytime. Most of the Netflix and Amazon I watch is in 4k now, and requires tone mapping. MadVR can't help with this.
But that isn't even the main reason I won't be using MadVR. The best thing about my setup is its simplicity. With just an NVidia shield player, I have ALL my content on one device. Everything from 4k UHD blu rays to upscaled network TV, and my projector never has to change sources, never even switches resolution. It just works. Oh, and it works pretty much identically in every room in the house, not just the theater.
For my girlfriend who is not the most tech savvy, here are the directions to use my system to its full potential:
1) Press the "Watch TV" button
2) Use the arrow buttons to highlight what you want and press the middle button to watch it.
3) If it has black bars on top and bottom, press the "2.35:1" button.
4) If it is "regular TV", press the "16:9" button.
5) If watching 4k UHD, press the "4k" button, otherwise press the "1080" button to switch the color/lamp modes.
6) Enjoy your content.
(3, 4, and 5 are for the theater room only, the other TV's skip these 3 steps)
99.5% of the time it works perfectly.
With the JVC and Paladin DCR lens, I will combine some functions differently (for aspect and HDR/SDR modes) but it will be the same basic functionality.
One last reason to not bother with MadVR: Despite rave reviews about how much better MadVR is at upscaling and tone mapping, I can't help but see it as an incremental improvement that is only really noticed by a trained eye. I don't consider myself a videophile, but I can see differences in quality video and let's face it, I have spent a lot of money on having a high end theater. My existing projector (Epson 5040) throws a pretty amazing picture already. Sure some think it is vastly inferior to a JVC or Sony, but I bet most people here would watch a movie in my room and think I already have a higher end projector. In fact, if it weren't for the 10gbps HDMI and the need for tone mapping, I probably wouldn't even upgrade. When I added the "harpervision" curve for HDR, it woke that projector up with 4k uhd content, and now I LOVE watching UHD movies in there. The JVC will be an upgrade, we all know that. But it is still an incremental upgrade. It's like going from a top of the line LCD flatscreen to OLED - better blacks, some nice features, but most people wouldn't see the difference unless you compared side by side and pointed it out. Furthermore, I will be adding an A-Lens for more light and better resolution on scope movies. That will be another incremental improvement. But once that is done, how much better can it really get? I am satisfied with the upscaling in the Shield, and the simplicity of it makes it even better. So as long as the tone mapping works decently in the JVC (and by reports it works great), why would I want to add complication, cost, and step backwards on simplicity just to gain some picture quality that I never knew was even missing and none of my guests would even notice?
As I said above, when MadVR supports HDMI inputs, OR PC's can start doing all the Android apps with all the features and bells and whistles (and MadVR can work with all of it), then I will be first in line to do it. I have long wanted to have ONE device in my theater for all my media, with one menu presenting all my options. I would love to have that with an HTPC, but you just can't right now. Until then, the Shield is the perfect device (for me), and you can't use MadVR (or even the Panny 820/9000) with it. You CAN, however, use a Lumagen Pro, so if by chance I really hate the internal tone mapping of the JVC, that will be my next purchase, despite the high price tag.
For anyone who is used to having a whole bunch of different sources, has easy access to their rack from the theater room, and/or likes to tinker with complicated systems, MadVR or the Panny players sound like really cool additions to your theater.