"All diffs were created equal"
To most people an LSD is an LSD... far from it
Viscous LSD diffs are considered "modest" performers when compared to either plate or torsen diffs, (much better than an open diff though)
Working by plates submerged in a "shear" fluid, viscous diffs relay on a differential in speed where as both plate diffs and torsen (especially) work on torque (real world)
Manufacturers like viscous as they are cheap to make (in comparison) and have few wearing parts however they have inherant limits as to what they can handle (power wise). Plate and torsen diffs however can be built to handle almost anything
I guess you gets what you pays for
Dont forget that Scoobys have 4 wheel drive so power gets shared out 4 ways (and weight to be moved) rather than the 2 ways (as in a zed) so 300 HP in a Scooby (approx STI spec) = 75 per wheel (assuming 50:50)
200hp in a Z = 100 per wheel or 25% more per drive shaft and more weight per axle to move
Due to the way they work (plates in a temperature reactive fluid) viscous diffs can take a split second longer to share the power out (the plates need to heat the fluid to provide a "shear" state and hence a reaction) than plate or torsen diffs so for a split second most of your power can be going one way
so just make sure those shafts are good and strong
On the plus side it will entitle you to have your wheels sprayed gold and to hang around in McDonalds car parks