I'm the OP and have done the Atmos upgrade to my HT. Thought I would revisit this thread and provide my feedback after having made the changes.
You have to read to the bottom to find out.....:-)
My existing theater had a 7.1 system. Polk audio RT5000 system with voice matched RT3000p mains, CS1000p center, FX1000i side surrounds and a set of the RT3000p satellites (without the powered subs) for the rear surrounds. I originally bought this setup back when physically matching drivers was the best way to set the groundwork for a good sounding system....pre-Audyssey, etc. Pink noise and a Rat Shack sound meter....... And a pair of SVS PB12/Plus-2's, with 2x12" drivers, each.
I had to replace my Onkyo PR
-SC-5508 with a Marantz AV-7702 MkII to be able to decode Atmos and DTS:X, and feed the 'top surround' signal to my amps. Bought a new Emotiva 5 channel amp (BasX A-500, 110WPC) to run the new top speakers. Added 4 x Polk RC80i speakers up top, as Polk recommended to get close to a voice match with the RT5000 system.
What it cost me:
I bought decent used gear when I could find it, and did the install myself. Don't know how I could have done it much cheaper, and could have spent a LOT more.
Used Marantz AV7702 MkII - $800
New Polk RC80i x 4 speakers - $240
Used Emotiva amp: $425
Wiring, connectors, etc.: $50
(Where else could I have spent $1,500 in my HT and maybe gotten more bang for my bucks? 100 new BD discs? A big dent in a JVC 4k e-shift projector? Netflix or Hulu for the rest of my life? )
To do an evaluation of the new setup, I went through my BD collection and marked each of the Atmos or DTS:X encoded discs based on info from the Dolby and DTS websites. 40 or so. Over the weeks since the upgrade I've re-watched a lot of them with the new top surround channels. I also use the 'synthesized' top channel modes when watching non-top surround encoded material.
The verdict? There have been a few "wow" moments from native-encoded discs, like when a helicopter flew overhead and the top channels were active, but for the most part, I've been fairly unimpressed. The capability is there, and when it's utilized the results can be really compelling, but the folks doing the sound mastering seem to be focused elsewhere. The upgrade has shown me that the top channels can add a lot when they are used.....but that's not very often, unfortunately. Shutting off the main amp and just listening to the top surround channels is usually disappointing.....very often not much, if anything, is there.
So, if I were designing and building a new, ground-up HT on a budget
, I'd prioritize the top channels somewhere behind the rear surrounds for 7.1. I'd also save myself a lot of coin by looking at a quality non-Atmos capable AVR or pre-pro. There's a glut of great sounding used non-height-enabled gear around, for pennies on the dollar. (Because people like me upgraded... :-) ) 5.1 and 7.1 systems still sound great, and actually have sound mastered into the surround channels for you to hear. I'd pre-wire for the top surrounds, of course, but probably not pull the trigger until (if ever) the folks making movies start using the top channels more. There are lots of other 'better bang-for-the-buck' ways to spend your money, IMO. If money's not an issue, though, go for it.
Other's opinions and experiences may be different, and I certainly respect that. Just one man's opinion....and this is something that I would have liked to have seen before I pulled the trigger.