Remember also that different types of superchargers have different characteristics amongst themselves...
For example a positive displacement supercharger such as the roots type blower on the L67 generally provides more low down torque, at the expense of lower efficiency and an increased intake charge temperature.
A centrifugal supercharger will have less torque down low due to the design relying on the momentum of the air (which is reduced at lower revs) but has a lower intake charge temp and therefore will produce a little more power for the same boost pressure.
Another point to consider is that the argument that you cannot cool the intake charge with a supercharger is absolutely NOT true. All centrifugal type blowers can be intercooled and even the Eaton M90 on top of the L67 can be intercooled using a special adapter plate that bolts between the blower and the intake manifold.
All in all, it depends which you prefer more... Instant kick in the back from the moment you press the pedal, or having to wait for the turbo to spool up and then copping it. It also depends if you like the wank factor of adding a BOV and getting "psssssshhh" when you back off the throttle.
Each to his own really, but my personal preference is the supercharger simply for its instant power, and also for its own wank factor of the oh-so-delicious whine coming from the intake when you nail it.
