ok, youre right. i dont know anything about stock cranks. theyre fucking horrible! all hail needle bearing failure, which is actually a pretty common problem on these cranks. i see way more threads about that than "my stock crank gave up on me"
i trust stock honda/yamaha/whatever needle bearings with my life, but i've seen enough "my puch needle bearing blew up" threads on this forum to think that if youre just building a 45-50mph daily rider, the stock crank IS sufficient, and probably the safer bet if youre not trying to get as much performance out of your bike as humanly possible.
that said, im getting an aftermarket crank for my next build, needle bearings ARE better than copper bushings, i just question the quality of the ones in some of the puch kits. youve still given me no legit reasons why stock cranks are bad yet, i agree a copper bushing is inferior to a needle bearing performance wise, but for a not-insanely-fast bike i see no real problem to it.