I used to have a SC Cobra (terminator) and now have the boosted performance Z. As much as I love my turbo set up, sometimes I miss the predictable power of SC.
As antivenom (my brother) mentioned, we are excited to run them side by side at the track and do some honest comparisons. I am sure there are guys on the forum that are turbo experts and can speak for running smaller turbos etc.
This seems to be a good thread on the subject:
370Z Supercharger or Twin Turbo
I however plan on going up in HP in the future. (600HP range) Guess my old HP junkie days are not out of my system. Antivenom is a far better driver than I am so I have to make myself feel better somehow.
I recently had to upgrade my tires etc to make the power more manageable.