The concern is, just because it works for you, doesn't mean it will work for all of your customers. Especially if they're not in the EU.
I'm not so sure on the cooling either -- their hard disks are very hot (I admit I don't know enough about hardware to say whether this is a problem) but generally I don't see many hardware failures.
I do however see plenty of random reboots -- only the HG servers (and strangely a few 19.99 servers with over a year uptime) seem to survive these as you'd expect.