I have long bought Yamaha, but bought an X4000 last weekend.
I like the audio compression so far, I was always reaching for the remote on the Yamaha during loud scenes. Jury is still out, but looks good. Setup is very well done on the Denon, but you will still have to take time to go understand what needs to be changed, as it's setting all speakers to large ( a no-no in my book.) Given the current info I have, I set them all to small, with an 80 hz crossover ( except for the left/right towers, I set them to 60.)
I missed having the power outlets like my Z7 had. Not sure if the higher aventage models have the aux power outlets.
Display is good. Remote layout is good and overall good, but the labels are hard to read for me. I either need glasses and light, or memorization
Price was good on the X4000 (compared to MSRP.) Local dealer sold me one for what looked like the going price.
X4000 power output does not impress given the MSRP. I am mostly using external amps, and figure I would not run out of power even if not using the amps, so this is minor. Denon always did seem to be the most expensive mainstream AVR ( compared to Yamaha, Pioneer, Sony etc.) On the other hand you get Audyssey Platinum, which seems like a good feature set.
I guess if you love Yamaha, I can't say anything bad about it. Over time I will maybe have a better idea of how well Audyssey works in my own setup and come to some conclusions.