I can say I've noticed a definite increase in controllability of my aircraft when I pinch, however I thumb as I found pinching felt quite uncomfortable for me, and I kept kicking rate switches with my fingers all the time.

Just couldn't deal with it. These days I fly thumbing it, with the tranny hung low and clipped to my belt on the base and neck strap to allow the tansmitter to hang about 15° down.

very comfortable.