you dont need anti lag in between shifts. They dont use it in drag racing so I dont see why you would need it street racing.
Garrett turbos hold up pretty well, all these companies come out with new things that are supposed to be better than the garretts but no one has come out with anything thus far. All the big guys in sfwd are running garrett turbochargers. Anti lag is pretty hard on the turbocharger but who is holding it for long periods of time? Its not like a 2 step that you have to be on to build boost, with antilag its just that.