Twist is the champ once you learn to use it!!
The deal is the twist is better, but some people just cant get used to it, you'll either love it or hate it but dont waste your time putting it on unless you committ to leaving it on for a min of 5 long rides after that you can make up your mind. Also depends on how you ride, if it's all technical short jaunts at a time then keep the thumb. If your like me and are running full throttle for long periods of time, like desert racing, then a twist is a very good mod. I love just grabbing a handfull of throttle leaning back and letting the bike do all the work, it evan made riding whoops eaiser!!