The above parameter defaults to 490Hz for multicopters. However I have a Hobbywing 20A quad ESC (4 in 1) and on this page for it;
"- Refresh rate of the throttle signal : 50Hz to 432Hz (432Hz is fast respond for Multi-rotors)"
Would it be a good idea to reduce RC_SPEED to 432 at the highest? What would be the problem in setting it even lower than this?