I didn't read this thread all the way through but I'll speak of my AVM-70 experience and throw in my $0.02 on the 90. BTW, I should qualify my statements with I do NOT believe all amps and processors sound the same, I believe UI has an impact on the performance of a product and I don't believe all things that measure well sound better than things that don't (specifically in my user experience Denon A110 in preamp mode compared o the AVM 70 and Gustard X16 vs Denafrips Ares II, so if that isn't your cup of tea I ask you to please scroll on).
I went from MRX-520 to NAD T758.3 to Marantz 7703 to AVR850 to X3600 to X4700 to A110 to RMC-1L to AVM-70. I have no plans or desire to upgrade (my processor) anytime soon. The Anthem flat out works, 90% (or more) of the "bugs" you read about are user error and Anthem has been very methodical and appropriate with their firmware updates and are keenly interested in and responsive to user inquiries / experiences.
I could not get any of my Denon/Marantz stuff to sound as good as the Anthem, even when using them in preamp mode with the same amps (which I have since changed too) and also in full analog bypass mode using an external DAC. Say what you will about placebo blah blah, I have been around long enough to discern my own experiences.
The latest beta update from Anthem including phase and polarity for subs along with auto-delay for all channels is freaking great and has worked flawlessly on my rig. Without upgrading at a significant cost I can not expect my room (well planned and properly treated) to sound any better than it does today, at least for multi-channel music and movie playback.
Lastly, the WebUI is excellent and ARC (after appropriate learning curve) is superior to my personal experiences with Audyssey (haven't used the new web based module) and Dirac (never used DLBC). The flexibility inside ARC and ease of setting up user profiles is great.
Two additional points; I use both a 2CH profile via analog bypass (no room correction, external DAC) and a 2.2CH digitized profile with ARC engaged from the same source. The two are closer (I still prefer pure 2CH in most cases) than with all the other processors referenced above, possibly due to Anthem's ADC implementation? If wishes were fishes I'd want balanced inputs but with my gear and being a short interconnect run its not a big deal.
My final point is I have heard from others the 2CH (digital) performance of the 90 is superior to the 70. This could be a real boon to those that prefer to use room correction for music. Otherwise I am not sure how to justify the difference in cost between the 70 and 90 or the 70 and any other processor for that matter.
Hope this is somewhat helpful and D+M fans and measurement peeps don't ruin this thread.