In general, forward pitch of the thumbhole will require less squeezing of the ball to keep it on your hand. As stated above, the thumbhole should still fit properly. An overlarge thumbhole will force you to squeeze no matter the pitch.
If you do plan on trying forward pitch with your thumbhole, I would suggest trying Ron Clifton's method which worked wonders for me. Start with your current thumb pitch and pitch your thumb forward 1/4. If you can throw that with no problem, pitch it forward another 1/4. Keep doing so until you struggle to get out of the ball cleanly, then backoff to the previous amount.
You should also consider shortening your span as you pitch your thumb forward, it will help create a relaxed grip without the need to squeeze to hold onto the ball.
Personally, over the course of about 7 months, I went from 3/8 reverse to 3/8 forward and shortened my span a total of 1/4 inch in the process. It definitely helped my game and tendonitis.
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J.J. "Waterola Kid" Anderson, the bLowling King : Kill the back row