Very good reading and closest to "engineering level" explaination I've seen on forums. Please continue to school us... it's very educational and being appreciated.
So, from reading the links from the DSM forum, it sounds like the helical LSD will wear out faster than the clutch ones (generally speaking, as there are obviously many variables: clutch pressure, clutch material, helical teeth angle, etc)?
Are the clutch LSD's then the the only way to have an electroncally controlled LSD?
Is the VD chosen for regular cars (like the WRX) because it is the most economical/long lived LSD for an AWD system and not because it's a "best choice" for the general use application?
On a side note, why did Lotus feel that the Elise did not need an LSD and autox'ers who run the Elise think it does?