Most of these don't just send they write it out then you confirm. Even current ALS bleach systems have spell check and basic predictive functions. You won't find it terrifying you will find it a relief that can speed up your talking. What you will find terrifying is how hard it is to talk.

ALS is a horrifying and typing with your eyes is slow and makes it hard to socialize at all. Predictive sleach even if it speaks before you are ready you can correct it. If it means being able to hold a somewhat normal conversation would be a life changing breakthrough.