no grips here. last few years i've gone back and forth. beginning of this season, i used grips and i was struggling with my consistency. seemed like my mistakes were amplified by the inserts. anyway, switched a little after the season started to non grips, and finished the year with my highest average ever (231). so, for me personally, no grips is the way to go, but it's really all about feel and what you're looking for when it comes to your release.
i do notice that my equipment hooks a touch less with no grips, so if you're simply looking for revs, go with grips. if you'd like a little harder, more consistent feel (for me anyway) you might like no grips a little better.
personal preference though.
Matt