I've owned or listened to just about every brand at one point or another, including Bryston, Mark Levinson Anthem, Classe, Acurus, Krell, ATI, Yamaha, Onkyo, Sony, Pioneer, Harman Kardon, Outlaw, Emotiva, Marantz, Denon.
But I've owned more Denon's than any other brands, mainly the Denon 3000s, 4000s, 5000, and AVP-A1.
I also recommend Denon to all my relatives and friends.
Of course, there is really nothing wrong with buying Yamaha or the other brands either.
Regarding Audyssey, I do run Audyssey, but then I bypass Audyssey by setting to "Audyssey Bypass L/R" + Dynamic EQ. This way, mainly the bass and a little bit of the treble is affected, not the rest of the frequencies.
So after you run Audyssey, you have 3 choices of Audyssey:
1) Audyssey
2) Audyssey Flat
3) Audyssey Bypass
You can use Dynamic EQ with any of them. So keep Dynamic EQ on. You will get to choose the different OFFSET settings that will control the magnitude of the Dynamic EQ.
Always turn OFF Dynamic VOLUME, because this will just compress the sound.
I have listened to a few Room Correction software. My wife's uncle likes Emotiva, so he has DIRAC. I've also listened to Anthem ARC (my brother's friend owns one). I've listened to the Pioneer Room Correction, Yamaha YPAO, and Harman Kardon Room Correction. When I bought the B&W 802D2, the dealer had McIntosh using Lyngdorf.
I know a lot of people will disagree with me, but that's just my own experience.
And until I can actually HEAR a significant improvement (not minor difference), I think all these room correction software are just gimmicks.
The only significant improvement I've ever heard is from Audyssey DYNAMIC EQ (DEQ), which will mainly boost the mid bass and a little bit of the treble. To me, the improvement is night and day.
That's my personal experience and the reason I would never buy anything without Audyssey Dynamic EQ - McIntosh, Marantz, Denon.
The almost-50% off MSRP and the better power output on the Denon X4300 is a plus, but not my only reason.