Choking up on the grip doesn't really work.
The problem is when choked up, WHERE exactly are you? And with no buttcap on the heel of the hand, you need to grip tighter, making a different tighter swing at the ball.
Then on returns of serves, where do you grip? You gotta cover wide shots as well as body shots.
I find most of my peers can handle an extra dose of power and spin, but they can't handle better placement and smarter shots. Meaning, a little more power is nice for the ego, but in the overall game, it makes very little difference.