I had the upgrade. I drove 45 minutes across Houston to one of the "better" Denon places, where I discovered that Denon had not taught them anything about this. How bad does it get? Well, they installed the hardware, put some stickers on the front of the unit, then forgot to flash the memory in either the unit or remote. So of course the unit wouldn't work. This is not a simple firmware upgrade. This is a mechanical upgrade. Bigtime. I can't honestly say I hear any difference, but it did do one thing that makes this receiver still the king: it added 3D. The new (included) sound test microphone and its purported ability to sense height as well as other old spatial things, well, it's bigger. the cord is too short so forget about using it in a big room. Which is a problem. But frankly no you cannot do this yourself unless you are a stereo repair person. Frankly you have to do it if you have 3D source material you want to see and hear without buying a new stereo. I would still say that this was a dubious purchase. I long for my old, old separates and new, high-tech decoder. The sound is no more smooth or accurate than before. Despite pictures that suggest the contrary in websites, the onscreen menu is still cumbersome and it looks exactly the same in almost every component. And now I can't get the ethernet jack to connect. Who knows, maybe Bubba disconnected it. Ultimately this is a very interesting upgrade. Big but horribly written manual, lots of stickers -- for either 5308 or its replacement -- and even a CD, which I suspect contained the firmware but who knows. Either way, I'd say this thing is still worth (at market) perhaps 1/5th what we paid for it. I used to have a Sony ES9000, the super model of that BIG COMPANY. It was HUGE, and its amps were marvelous, and its sound quite nice. But of course it went out of date with HDMI. Maybe we get another 2 years out of the Denon now. But this is the first time their upgrade has actually been what they promised - "future-proofing" a $XXXX purchase. And it is disappointing. I'd love to see what an upgraded unit sells for on eBay. I'd trade my Denon 5308 with upgrade for some tube amps and a processor any day of the week including Sunday. FWIW.