The ability to pull different weights is mostly because with the thumb release you have to hold the weight in your fingers, with a strap/wrist you don't. Takes a bit of getting use to but you will soon be able to draw it easily.

For the guy who said he would flick the trigger, easy solution, don't put your thumb on the trigger.

do yourself a favor and set the thumb trigger to have no travel in it before it fires, if it has travel you will feel it during the pressure build up to firing it and it could lead to target panic. You want it to break clean without any movement before the break.