Why the fuck would you run in to compressor overspeed? Youd only do that if you specced it all wrong, and only time youd ever spec it so its that bad is if you used a centrifugal supercharger as they give fuck all low down, and anyone who knew what they was doing (see above for examples of not ) would never do that.

ALL sucsessful twincharged engines use a positive displacment charger for this reason, and geared in a normal way like it was running alone right thru the revs.
How hard you push it will depend how you want the car to drive etc.

Wat you are suggesting is complex and not all that good, esp as you miss the main plus points of twincharging doing it that way.

I know people and companies that have sucessfully done it, and also tested it cutting out with an electromagnetic clutch etc, and the way I say is the best way by miles still.

Im not guessing, im going from real world proven stuff.