....
i've been all over the place with grips (and lead tape, but that's a different topic).
i have big hands as i am 6 foot 2....
i've gone back to smaller grip 4 1/2 as with larger grip, you can't get the snap/spin on serves or groundstrokes.... to hit the ball completely straight easily, then bigger grip is better...
also, i got tennis elbow from larger grip. here's my theory: with bigger grip, you can't use wrist for spin too much, so i think you use "elbow snap" or something like that.....
it is strange as i always liked bigger grips as it's pretty straight-forward to hit the ball straight, but i really think i need more SNAP and SPIN on my power shots.
just my two cents...... and from all the reading i've done, seems almost all pro's play smaller grips, except maybe pete sampras, which i find surprising (how's he getting massive spin on his serves???)