I have a Breakaway also, and while it fits my R3T perfectly, it won't (and never has been able to) hold the throttle at a given position. It can't seem to overcome the throttle spring back pressure - the throttle is just too heavy. I've reset mine according to the directions several times - and it still won't hold - the speed always scrubs off at the rate of about 5 mph every few seconds.
Nice device - extremely well made and cleverly engineered, even nice looking when installed - but just not a good piece of kit for the R3T.