Yeah, I've seen the grounding issue discussion too, definitely cause for concern. Also, seems that I've heard some issues with the Audysee on the AV7005 with low levels but don't really remember what that was about.
What is it about the Denon 4311 that you like over the Marantz? Is your advice to stick with recievers (even if just for pre/pro) and not a dedicated pre/pro only?
A lot of other guys can talk more about it. But I see 4 advantages off the bat.
1) no ground loop hum that I know of
2) Audyssey XT32 w/ dual sub EQ (Marantz is XT w/o dual sub EQ)
3) 140wpc (Marantz is 125wpc)
4) 38.2lbs (Marantz is 28.7lbs)
1st, I see nothing wrong w/ AVR or pre-pro. Both would be the same to me I terms of SQ. No right or wrong.
But AVR also has backup internal amps just in case. And in most cases, you won't need more than 140wpc.