Hi Laurie, and welcome!
I can't comment on the Denon, but I do own a Yamaha. As much as the experts don't recommend them for a 4ohm load, mine has been bullit proof driving the M80's for over 3 years now. It has never given me a second of trouble.
As far as the interface goes, it could stand to be better. I am used to it now, but it's still not that good. For example, I can't help but play with the sub levels THROUGHOUT a movie. To do this, you need to enter 2 to 3 keystrokes AND watch the display every time. Pain in the back side.
I used to long for an HK, but with all the reports of quality demons, I've had a change of heart. When it comes time to change, I'll be looking at Rotel or even Axiom when they finally come to market.
