"There's a reason dirtbikes, mountainbikes etc all use levers for controls and not thumbs." I have to agree with this having been a long time dirt bike rider. I think I would prefer utilizing my finger rather than thumb and will be interested in giving it a try. I understand that the thumb is the most unique digit of the hand and confers the ability to grasp. It is grasp that I believe to be the primary use for a handle bar.
In summary, the thumb is the hallmark of humans and separates us from primates, so unless I plan on hanging from trees I think the finger throttle would have advantages.
In summary, the thumb is the hallmark of humans and separates us from primates, so unless I plan on hanging from trees I think the finger throttle would have advantages.