Actually, I think it’s the opposite, because Pickups were created after. 
You can overdub many times with Pickups.
With Flex, when you apply fx, it can get muddy / dirty after 15 / 20 overdub recordings.
Yes I think I had that without pitch mod, OT master clock. 
I don’t like the fact Pickups don’t play when I press Play button.
I think it’s possible to make an overdub undo with 2 Flex tracks and pattern changes.
It works with individual tracks.
Pickup machine double tempo - #13 by sezare56