The drag the SC produces will vary at different loads as it is not a constant. I HIGHLY doubt the CTSC (or like) is using 200hp to turn the blower. I'd image on some of the higher boost setups with the blower, it would be roughly around 50hp +/- 20hp.
As far as comparing a turbo to an SC... A turbo will relieve the physical drag that the SC's have, but there are other variables to determine exactly what the parasitic loss is when trying to compare numbers between the two. Looking at IDC's (given they are the same) in reference to RPM/load/boost between the two (turbo/SC), you could probably get a better idea of the loss instead of comparing max boost vs whp.