Tstormdiver, my point exactly.
Just try removing your mask and put it back on again in 8 celsius. Imagine how much worse it would be if you needed to take off your hood first.
Another reason to change masks could be that it's fogging.
It can be done, however with some training & practice. The bottom (below 60 ft- 20 m) of the quarry I dive frequently is a solid 42 degrees F (5.6 degrees C) year round. I had to swap masks at 90 ft (30 m) for my Adv. Nitrox/ Deco course. Yes,... it was a pain in the butt & very uncomfortable, but was able to do it. I just pushed my hood back, took off the old mask & replaced with the back- up & put the hood back over my head. For the diving I do, that is a reality. I do practice the technique from time to time, to keep my skills up.