SA's are very useful and how worthy they are to you depends on your tactics, formation and players.
I disagree that scout keepers are worthless. They always have 1v1 or penalties and I have saved penalties before, with and without them but, and I hate to do this, real life goalies dont save many either, even specialists like Reina. He might save 2-3 out of 10, when a regular GK might save 1-2 out of 10. Same for T11.
Plus, they are higher skill points defensively, like positioning and handling. So overall it is useful to have the best possible GK.