Dave, I can't 100% answer this question as I don't know what the original intent is. I can assume you are correct as telemetry that can not be used to enhance aircraft performance should be OK as that would make most sense but you know how these things go. That being said, the few pattern contests I have flown in the past 2 seasons have been with an A9 TX that has the RX battery voltage monitor and nobody seemed to have issue with it. IMO what would not be OK would be airspeed, altitude, attitude, main battery consuption and the like.