castle creations is one of the best brands out there imo. it's response time is pretty fast, or at least it seems to be. brushless controllers are just going to be a little slower than brushed controllers i guess becuase it has to figure out the timing whereas the brushed controllers just keep the gate open longer. in reality you probably will not find one that is really super fast because they are designed for planes, where it is not quite as critical, and a 1/10th second delay is acceptable. for us, it is not. If you can find something really fast, i would sure like to know about it, because i can further enhance my motor precision by eliminating the small dip in the power curve when pitch is applied.