Been trying to do some research into the wastegate, seems promising but not much supercharger related info out there.
The general consensus seems to be that having the pulley set to boost to say 15psi, then have the gate limit engine psi to 7 or whatever: Because the charger is spinning faster, you get more boost earlier in the rev range and it builds quicker...
The only possible downsides I think were hotter air from faster charger, and I guess reduced service life...