Bye bye, Marantz.  Welcome back, Denon.  Goodbye to many wonderful new features I enjoyed.  After a couple of weeks of effort, I simply could not get near the SQ I was used to with the old 4800, which is, admittedly, a somewhat higher-order piece than the new one.  I spent a couple of hours configuring the Audyssey system, to some good effect.  But for direct, un-EQ'd listening, I could never get the bass to sound substantial in 2.0. whether I set the main speakers to Large or Small, set the sub to Off, toggled LFE / LFE + Main, etc.  Additionally, I was surprised at the decrease in Zone2 SQ:  I hate to say it, but even ceiling speakers seem capable of delivering PRaT when the pre (even an older Japanese example) is up to it.
 
I will never take the pre section for granted again.  Who knew that an old receiver could better a newer, dedicated pre-processor?
I hate returning stuff like this; and what a chore swapping in and out.  Now I am a little gun-shy; and I think the next step up at the Marantz dealer is a big Denon or Mcintosh for relatively huge $.  Maybe providence will deliver an easy-to-demo p/l AV2, if I am patient and lucky.  
 
Nick