I've tried it both ways, I've gone back to Vise P/O inserts, easier on my tender fingers, plus I'm able to get more revs on the ball with inserts and less damage or wear and tear on the fingers. Gone back to hard urethane slugs, less sticking or hanging up in the summer time. My thumb size goes up and down on a nightly basis, "like its that time of the month", the hard urethane slug is smoother and has less friction on the thumb for me when it gets humid and warmer, thus I get a smooth unhindered release.
