My answer to the original thread question is 'I have no idea.'
Because for a player with average swing speed, I have no doubt that the majority would hit driver farther if they hit slightly up.
It is easier said than done, for sure. What has worked fairly consistently for me, at least in terms of hitting longer drives, is addressing the ball with the clubhead about 6 inches behind the ball. That seems to make my brain at least attempt to bottom out the swing a few inches behind the ball.
If you are having trouble with driver, give this a try.