I personally use the Onkyo 607 at home and have no problems with overheating.
It's a beast of an amp and providing you have the patience to tweak the settings after the auto-cal is finished then you will be well rewarded.
IMHO there is no better connected amp that sounds this good under £1000 and considering I paid £350 for it that's quite a bargain.
It IS a big amp with a huge power supply so make sure you have adequate ventilation on all sides and don't hide it away in a closed cabinet, but then again that holds true for any components you may have!
With great sceptisism I even added the two extra "front height" speakers to see if they made any difference and was pleasantly surprised
So to sum up the 607 has got spadeloads of grunt, sounds very accurate when you bi-amp the front speakers, is ultimately configurable and at a great price point.
Go and audition one with your favourite music or film, or ignore it at your peril!