I use shot pal from time to time. I find it really helps esp with short irons shots to be able to dial it in. I don't want my computer to have posts and junk on it so I'll gladly pay the fee for it.
It is simple to turn off, I don't understand why people complain when they get something for free. it's like the free balls that WGT gives out, don't use them if you don't like them.