star61, the first pull in OL doesn't determine the success of the lift. It's all about the explosive 2nd pull. Besides the first pull isn't meant to be explosive. U just squeeze the bar off the floor, then you explode vertically through the hips.
I' ve heard that front squats have a better carryover to mechanics of the pull in the clean (?). U can't cheat them either and a really deap front squat is a better indicator of leg strength than the back squat..