Just remember that location of the balance hole will likely play a more important role than size if you are trying to alter the reaction of a ball:
Mo Pinel's guide to balance holes:
Brunsnick's video on balance holes:
Other info I've gathered through the years (my apologies that I can't give proper credit for the following):
a weighthole on your positive axis point will cause the ball to roll up sooner
a weighthole between your positive axis point and your grip will remove top and side weights allowing the ball to react smoother and will flare less
a weighthole past your positive axis point will increase backend reaction and length caused by more flare
Just as you could pitch a thumbhole, so could the weighthole be pitched.
Pitching the weighthole away from the palm preserved more top weight in the ball thus enhancing the backend and the hit of the ball.
Pitching the hole towards the palm caused the ball to lose more topweight and thus making a smoother reaction.
Pitching towards the thumb will cause more length and a sharper backend reaction. Pitching towards the fingers will have an opposite effect.
The current way of thinking if you are strictly worried about getting the ball back within the legal ABC limits is to place the weighthole at the intersection of a line drawn from the grip center, through the CG to the vertical axis line. A hole placed here will stand a 95% chance of getting the ball back within the limits.
