I ran Audyssey a few times with the Denon AVR-A100/4311. It always sets the sub 3 db below the Onkyo 5008. All the other reading are close to identical between the 2 receivers. Two frequency sweeps using an RS SPL meter showed a 3 db increase over the Onkyo at 5 KHz
I did a lot of back and forth listening tests, mostly in stereo and found the Onkyo to be the winner. Both units sound close and continued listening to either unit would satisfy most. But I found the Onkyo to be slightly more lively and dynamic in comparison. I think this may be due to the 32 bit DACs and the 3 transformers. As far as heat goes, the Onkyo is warmer in one area and cold in others. The Denon is warm all over. The total heat output is probably close to the same. A couple surprises were the speaker binding posts look identical. The front plate on the A100 sparkles in the sunlight. For me that is where the sparkle ended. In the end it is like comparing Garmin with a Tom Tom GPS. If you like menus, then get the Denon. If you like convenience and being able to adjust Video, Bass, Treble and Level on the fly, get the Onkyo. I don't think you can adjust the tone in Audyssey with the Denon. I much prefer the remote on the Onkyo. The Denon will drive 11 speakers with the addition of 2 more amps. With the Onkyo you have to give up the back speakers if you want high and wide at the same time. Denon seems to do the DSX setup a lot faster. May be more accurate, takes distance down to tenths. Denon wouldn't allow a 70 db crossover, like the Onkyo. With the graphs, I got what looks like the same results using a tripod and a mic boom.