This is opinion of course...
I have a thumb throttle, and like Dogman in some other thread, position it so that at full throttle, the thumb is in a natural grip position. The intended position for these things seems to be to have the idiot lights visible. In that position, the thumb is in an uncomfortable position, but I had to give up the idiot lights. I have twist shifters so the thumb throttle is the only real option. I'm used to it now, feel safe and comfortable with it.
But I just built a bike with an ezee kit for my wife. This is a new Costo Schwinn and I picked the half twist throttle -- it has quickfire shifters and I've not enough thumbs. It's Ok, except old habits die hard and when it's time to give 'er the gun I tend to shift gears instead.
Glad I did not get the full twist -- reason is safety during ground handling. The on/off switch on this kit is way in the back and you have to get off the bike to get to it. Since it's normal to handle the bike by the handlegrips, with the motor live and you standing beside it it would be real easy for things to get out of hand.
And gimme a day or so and I'll send out an ezee report...