I recently bought the SR 8001. My previous receiver was a HK 745, which replaced a HK 7300, which replaced a HK 7200 (I like HK if you hadn't guessed). I'm running Axiom speakers in my HT room.
I'm not certain, but I think the only difference with Audyssey is the 'Pro' version and standard. To step to the Pro, you have to go to the 5XXX series Denon's....I THINK. My Marantz uses a six position set up where you place the mic in six different room locations. The pro has eight, plus some other tweaks that I'm not really up on.
All that aside, I'm absolutely loving the Marantz. I don't normally praise receivers because I prefer separates. This Marnantz on the other hand sounds great. The EQ did help with my room as well. And, if you really want to tame down the high's, use THX. It rolls the high's off a tad.
But as Gene already said, you need to do what you can with your room first. I have hard wood floors in my HT and the room sounded horrible until I threw a big wool rug down in front of the speakers. It made a HUGE difference.
If you want some more info on the Marantz, I wrote up a mini review and posted it at the Axiom boards somewhere about a week ago.