Just a personal choice. I use a thumb throttle and am happy with it. On the left, since most gear shifting is made with my right. I like to keep two fingers on the brake lever, and my palm and other fingers on the grip. So its only the thumb that works the throttle. Works for me.
Same here. Thumb throttle on right. Keep 2 fingers on the brake lever. I still have my rear shifter on the right. Took off the front shifter as it was never used. I think I've shifted maybe 4 times in well over 6,000 miles. lol Gives me the most control that way. Rear brake lever is on the left. This setup allows me the most control. I would like to see a heavy duty thumb throttle come out.
I have a thumb throttle on one bike and twist on the other, and much prefer the twist throttle, the thumb throttle just feels a bit granddad bike opposed to motorbike.