not hard to deal with from a diy perspective ,starters are mostly a strip down and clean ,polish the commutator and recut segments then google brush length,if worn replace if beyond specs.
Same deal with altenator but replace bearings at each end ,cheap to buy and use good ones ,end of the day Bosch stuff is good and reconditions well.
Not sure about those reduction starters? and really do we need them ?not like the T4 has high compression or even the early six 2.0 for that matter,I would expect to see them pull less current from the battery which is a plus,a little concerned about durability ,time will tell