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!