If you're around for the next NSXCA meet in Huntington beach at Team NSX, you'd have a great opportunity to check out different types of superchargers and see what you like best.
Alex has a GruppeM Supercharger and he is always there. The cost is similar for both. You'd have a good time, see the different SCs available, and get to talk to Larry and other members about the pros/cons of each.
Larry's been known to squeeze quite a bit more out of both SC setups and knows the pros/cons of both.
It's too bad you missed the last meet. It would have been perfect as the theme was superchargers. They had three NSXs, 1 with comptech, 1 with GruppeM, and one with a Vortec, all opened up right next to each other. He did all three setups and talked about every aspect of each one.
From what I understand, the GruppeM produces considerably more torque because of the added airflow from the tubing, but it requires much more space so you lose the engine cover.
good luck