GJM,
I've been through TPC and apply their grip fundamentals. In relation to what you are saying here with squeezing your fingers less, are you referring too -
The strong hand C-Clamp or the support hand rear quartering?
Something Rossen (TPC instructor and CZ pro) told me about the support hand rear quartering is that he imagines he is trying to crack a walnut in between the base of his thumbs.
My current perception of what you are saying is that your C-clamp is lighter in tension and your rear quartering palm thumb bases are cracking peanut shells instead of Walnuts.
JM