FWIW... when I had my all-in-one running with teh stock hood/PCs, I had real issues with heat. The tightly enclosed hood made it near impossible to draw out the heat. There are tweaks you and do, and maybe the newer ones are better, but...
If you're looking at an all-in-one, consider one with a MH fixture. I had MUCH better luck maintaining my tank after I replaced the PC-stocked hood with the MH fixture. And most the corals did better as well.