I've got a set. They're OK - quite bulky and heavy but also solid and quite easy to clip with (I know that's a bit of a contradiction!). They are noisy although my previous horses never minded them, current horse really hates having his face clipped with them because of the noise.
Don't heat up at all really - I can hunter clip my 17hh IDx and they will only be getting slightly warm towards the end. They are fiddly when you take the blades off to clean, and I do find I need to take them off fairly frequently during clipping (probably something to do with my rubbish technique..?!).
But, overall I like them. I borrowed a set of Liverymans with a battery pack (and I think they had fixed blades? Might have been Harmony model) when mine were broken last year and I preferred my Heinigers.
Got a set of mains Handy Clippers and must have had them 15+ years. Always liked them, the blades never get hot and not overly noisy. Don't be tempted (as I did) to run them without the blades on as it screws up the gears.
I've been pleased with mine, they are fairly heavy to hold, but I think they are very powerful. The blades are a doddle to change and they are quiet to use.