They play really well together. The mid range drivers in the 8060HD are smaller than the ones in the SM65, but are of the same design and still blend well together. I haven't had any issues with it moving due to vibration like some 8080HD users have claimed. Maybe if I ran it as large, instead of being crossed at 40Hz, it might move a little LOL. It's a pretty heavy and solid speaker though so it would take a good bit to make it move.
The reason I don't run it as large is because of my receiver. It's a Denon 1913 and when I set the SM65s to small the only options I get for the center speaker are "small" and "none". It wont let me set the center to large of the L/R is set to small. It seems to do really well with a 40hz crossover though.