Well to answer your question about a helical diff they can wear out and when they do they break spider gears and casing because of shock load. where as a clutch pack does not.
torsen have a big weak fall on a solid axle because on rough pavement they can disengage because one tire can lift and cause the diff to go open and make an unpredictable corner were you can not trust the diff because of axle wrap. granted ture track are sweet because they mimic ackerman streeing but lift and shutter is a issues with our trucks most blamed on our leafs. granted you can fix this with a wrap bar or caltrac system
all in all i am not a fan of a ture track with leaf spring plus toyota would have done it in the first place if it was better.
A clutch pack is like a a locked rear end tell you over come the tension of of power given by said spring and clearance of the clutch pack springs it wil all ways be the same no matter what granted n a high life of a tire it will lessen but on rough roads it will be locked.
soooooooooooo
steel plate vs carbon kev steel plat can chatter and has to be set up tight so it will not chatter,were as carbon setup are set up not as tight because of the carbon plates and give better tire wear and still give the same bite but they wear out over time
i think i am done now feel free to pick me brain kinda had a few beer lol