I know several guys a couple of which are very competitive racers that use the 9100s on steering . one of those guys who takes very good care of his equipment has changed his steering 9100s(due to glitching/twitching) at least once this summer . the other 2 have had good success with the 9100s on both throttle and steering . myself Im not going to take a chance anyway anyhow and just put a 9100"t" on both throttle and steering . friday , just before racing saturday I put the 9100s on my throttles and did like the extra response on throttle&brake . 2 things I like with jr and also racing an 8ight along with using other losi and horizon products is that when there is a reason for whatever issue I have they(horizon)knows when I call them for product info or whatever that I am using only their(horizon) products and I seem to get better treatment when dealing with them , and the fact that these servos have a 3yr warrenty . And when you have a problem with a z9100 jr servo send it to them and 90% of the time when they recieve it they will immedietely drop a brand new one in the mail for you .