The Glock 23/32 grip fits my hand pretty well as is size wise, but I did find undercutting the triggerguard made a world of difference in getting a solid grip on the gun. Since this gets your hand higher up and puts less of your hand on the palm swell it may act as a "grip reduction". You also may consider dremeling off checkering (and maybe a tad deeper) and stippling or grip taping it to regain some texture.
I have a standard Glock 21 and am considering dremeling the top part of backstrap where the web of my hand fits to alleviate some of the 21's boxy feel; however, I have not figured out how to do this cleanly. The trigger undercut is easy since the Dremel drum fits nicely in this space.