I'm still running 36Mhz (Futaba, PCM2048 G3) and can't say I've ever experienced a "hold" let alone a failsafe lockout.

However, if after passing the ground checks the plug cap decided to make a poor contact with the plug or the braid broke away from inside the cdi unit then I'd bet money any of the 72/35/36 Mhz systems wouldn't be happy.

I use the same li-po battery for the RX regulator and the CDI regulator, and ground checks (and now many many flights) have proven it to be ok but like they say, your mileage may vary. I've got a Castle Creations 85HV that's next to unusable on 36Mhz but many others have no problems with them????