I've heard that the digestion of grasshoppers stops when they are kept too cold. They told me the food inside the stomache rots which could be bad for your T's. I know people that don't feed grasshoppers for this reason, because they are allmost allways kept too cold in the stores. I don't know if this is true, I feed my T's all sorts of things. If this would be true then it's not advisable to freeze your grasshoppers. I know it's possible for crickets. I sometimes put them in the fridge for half an hour before feeding, it makes them a little slower.
My emps have been raised to 7I on frozen/thawed food. There are a few reasons I'd be hesitant to use feeders that have died especially wild-caught stuff eg. grasshoppers. I do freeze live healthy food for later use though.
I've tried this before a good while back. The prob seems to be freezer burn. The insects get dehydrated. I think there is something about that that takes away from a signal to a scorp that lets it know it's something to eat. The moisture, the moisture/fluids is appealing, that's what it seems like to me. So I froze a lot of hoppers and other potential food items in a baggy with water in it. That was too much of a pain because I had to thaw out the whole thing and had too much food thawed that wasn't going to get eaten. But they would pick it up when they messed around with it and start eating it, but not worth it at all to me.