Ben, I noticed that the HK525 is one of the few receivers that added channels, and the weight of the unit went up significantly from the previous years model. The 525 is 44lbs, vs 520 of 35lb. No doubt that the 525 has a larger transformer than the 520. They also dropped the wattage rating down 5, on all channels driven. (2 channel stayed the same) Looks like they are trying to keep valid numbers in the ratings game.
PS: Don't know how they are cramming all those power transistors and heat sinks in one box. I hope the battle for more channels (in one box), ends soon.
I would second Davids remarks concerning the Onkyo to be better at HT and the HK better at Music. It seems to be the prevailing notion. I too have a 797 and am quite happy with it. There is not even a hint of it lacking power. The Onkyo's absolutely rock for HT and are darn good for music.