2.4 Ghz is so easy to set up, you can set the idle speed with the travel adjust on the radio system. with a glow engine you have a battery, servo, on-off switch and a receiver. Install the servo and then when you start the model use the travel adjust to set the idle speed. Bringing the engine to an idle for taxi is an important part of the flight.
Then to shut down the engine use the trim on the transmitter to lower the throttle one more notch and the engine quits.
either way you go they both work, but Chuck is right if the lines go slack on 3-line you have no throttle control. I have had models ground loop on me easily 5 times and in all cases I calmly throttled back to idle and killed the engine with electronic controls. had I been flying 3-line I would have been running to get out of the way.
Fred