I can't disagree with the Marantz running hot. I have a SR6400 and need to leave the top open to the air it gets so hot.
But purely considering sound, which performs better?
The Marantz SR4500, which is rated at 80 watts/channel, retails for $430. The HK AVR 335, which is rated at 55 watts/channel, retails for $799. Even if you consider the Marantz power rating to be "overrated" the HK is still considerably more expensive. And I do realize Ascend will give you a discount if you buy a speaker package to knock the price down a little.
But it seems to me that the Marantz SR4500 would be the reasonable choice based on price. Is the HK sound that much better (or at all better)? I'm very impressed with my current Marantz and know them to have an excellent reputation.