I just have a couple random thoughts to add to this thread:
More balls doesnt always mean a higher load rating, sometimes just higher rpm rating ( IE- 10ball vs 14ball). go spend some time in the NTN catalog its pretty neat.
Koyo or ntn are the only bearings to run. skf =shit as far as im concerned. Having to replace everything because one failed gets expensive.
TDR is the cheapest place to get the ntn maxload bearings at $30. Most bearing houses cant get them.
the stock vs straight cut gears with the TZ seems to be a hit or miss. Why use a TZ then? because a roller bearing has a higher load rating. Wheel bearings come to mind here