[kenny rogers]

The helical type does have the best long term use. I don't know exactly how long it'll take to wear one out, but being made by Honda, I'm going to say it'll probably last as long as the tranny (my GUESS is 300k+... of course this is subject to power and abuse variations...). The reason I say this is because the "breakdown" will eventually come from wearing on metal on metal contact, not liquids or clutch packs.

side note, I used to own a BMW with a clutch pack LSD... those things go out at about 100k (sometimes sooner).