My AV dealer friend keep poison me with this new Denon 4311.

He ask me to sell off my Onkyo NR808 to replace with the 4311 and currently the Denon is having a promotion and giving away a free HP netbook.

So, if I get the 4311 and sell off the netbook and the Onkyo (which I got it at a good price during a trade show), I might ended up only need to top up a mere $80.

Would if be worth it?

How would one differentiates the sound of Onkyo and Denon?

How would the Audyssey MultiEQ XT32 perform and are there any bugs being reported as it's quite new?

This might very well be worth upgrading if you can take advantage of the feature set and if you have experienced positive results with Audyssey in the past. In my personal opinion Onkyo and Denon are two of my favorites.

I've only owned denon (a 3808) and I love it.

I wouldn't expect a change in sound at all. IF you like the features that the denon offers then go for it. I don't care for audyssey myself.