Did you ever try a tab ?, my calluses are going away since I switched and my accuracy has only gotten better.
Thought about this post, your probably correct " thicker sting smoother release". I purchased a Bear super magnum 48" and it had those rubber no glove release aids on the string, I tried to shoot it before taking those off the string and this was with a glove on, it shot very smooth and accurate right from the get go, something to think about, but remember thicker string = slower arrow, at least usually.