Telemetry is nice to have in a most impressive way to impress your friends or get real data out of it. Traxxas is nice but a mandatory Apple device is crazy....And running a 100mph XO-1 there is no way you look on the display to see if it is running that 100mph or else you can peal your car from a tree.

For racers only a battery voltage and motor/engine temperature is important but no way to check while racing, thats why there is no need to have a huge dashboard or telemetry at all. I must say the old Sprektrum systems with an handheld telemetry reciever was the best to give it to your pitman