I think it's smooth and is very easy to use. The thumb trigger is adjustable both tension wise and position. You can move it up and down depending on where you are comfortable with it. So with that adjustability it should fit you alright. I haven't messed with the tension adjustment at all. I just switched to this release after shooting wrist strap releases for 18 years and so far I am very happy with it. As for which one to buy, sorry I can't help you on that. You will have to decide if you want a shorter head or longer one. I didn't get a chance to try both ProDiamonds out.