I have one of those too but it didnt fit out of the box with my oxfords. Wasnt carrying it with me on the trip.
As far as accidentally hitting the throttle, it is really easy to spin the cramp buster around the grip and out of the way. If anyone is using that in a situation other than highway riding they are insane. If im heading for an off ramp i just spin it away from me.
Also, throttle locks/assists seem to be pretty polarizing. Ive seen more than a few people say they dont like the vista cruise because it actually locks the throttle. Others dont like the cramp busters cause they can get in the way. Personally, i think its just a matter of knowing how to use them properly.