I spent the dough on the Throttlemeister but unless you are traveling on a 'flat as a pancake' type road, your speed will go up or down with the rise and fall of the roadway...
I then 'discovered' the $9 plastic Throttle Rocket device..this just velcroes onto your throttle and enables you to just rest your palm on it and control the throttle giving your fingers as much relax time as you want..
If I had to do it all over again, I'd save the bucks on the Throttlemeister and just get the $9 device.
Hope that helps.. and now you have more of your hard earned money to spend elsewhere!