I wouldn't worry too much about heat at the sub 200 degree temps listed in the O.P. but as the temps get higher one thing I think would be a concern would be the possibility of warpage or distortion of the razor. It wouldn't take a whole lot of distortion at all, a couple of thousandths of an inch maybe to affect the quality of the shave. With the different thickness of the metals throughout the razors they might heat and cool at different rates causing the potential for problems. I don't know what the magic temp that problems start occurring would be, but I would guess anything over 350-400F could cause issues
