Been using inserts for 15+ years. Never noticed anything like that.

Different colors sometimes feel different amounts of gripping or friction. Different brands are sized differently and feel differently. Different models within a brand may also be different feeling and possibly sized.

 

The same brand and the same model and the same color always feel the same size and seem to me to have the same amount of friction against my finger tip.

 

Different balls do expand and shrink at different rates depending on the resin, the filler and so on. they may make the individual insert feel different once they are installed int he hole and glued in, but when I try them just by themselves, not installed in the ball, they do not feel different.

 

I've mainly use Pro Sports Contour Power grips and Vise-Grips oval/power Oval grips. So I cannot comment on Turbo 2-n-1 grips.