The reason why multiple people on here are saying Gripshifters are junk is because many of us have seen multiple examples of them breaking just do to shifting forces... but since losing the ability to shift is not a safety issue, it's a quality problem that does not affect safety. However, if you convert the weak-as-a-kitten plastic shifters into weak-as-a-kitten plastic brake levers... well, geez - if it doesn't seem like a bad idea to you yet then I don't know what I can say to pursuade you.
Please post pictures of what is left of your bike after you get out of the hospital!