I put an Ultimak mount and a Russian PK-02 red dot on my AK the other day but have not had a chance to shoot it yet, so I cannot say anything about the temperature problem, but I'm not expecting it to be a real issue.
The mount is very sturdy, easy to install and remove, provides a lot of rail surface, and is low enough to the barrel that I can use my iron sights without turning on my red dot sight.
I'd like to hear some more input from people who have actually used an Ultimak scout mount equipped AK, though.