I am flying with the ignition plugged directly into a spare port on a Futaba 2.4 Rx (608fs). I have a Futaba micro switch with a ferrite ring in line with the ignition unit for safety . You could use a switch on the radio to activate the ignition but it may not be as safe for priming etc ?

Setup: APC 19x11 cdi prop, 1,500-7500rpm, 30%nitro/10%oil, 460cc tank + 1oz hopper tank using ~ 320cc for a 10min flight in the wind. Needle open ¾ of a turn. 220mah per flight (6 servos/ignition, A123 1100Mah with 5.2v reg).