I really don't think your going to hear any difference between receiver A or B or C, as they all follow the same guidlines and regulations. The only time your going to hear something different is if you adjust the tone controls or use a built in feature that changes the sound.
I would purchase a receiver that has the features your looking for and meets your price. Back when the 80ti's came out there were some Yamahas that for whatever reason would shut down when driving the M80ti's to loud levels. I'm guessing the newer models of today, should be better.
Denon has never had a problem with 80's. I like the Audyssey Calibration setup of the Denon, Yamaha does not offer this feature.
randy
