I have a digital 1K going and mine puts off almost no noticable heat, and is as big as about 2 boxes of mack and chees and I atach it right to the wall, it is kind of like a little car amp. I also have 2 Digitec electronic 1K's and they seem like they are about 30LB's each and do hum but just a little, and we already no about the heat.
I haven't really been paying much attintion to other differences, but I will start being more observant and try to contribute some more input down the road. I may also replace the 2 Digitec with 3 digital 600w's and see how that go's. But all and all my digital is much more convenient IMO.
Adieu