I also don't like that these magnifiers stick up so far on a scope. They need to make these with a snap-on mount so you can quickly put them on and off. I have a spotlight on my pellet rifle that snaps on when the varmints show up at night. Works great. They are plastic mounts so they may not work well below freezing, unless you keep them under your parka until needed.
My biggest problem with glasses is they fog at the worst time. As buck-fever sets in and you start breathing hard they fog, if climbing a tree and heating up they fog, if looking down at game they fog, if you have a mask on they fog.
I've sprayed antifog on them, dish soap other home remedies, and they still fog.