Pe reivers
Before poo-pooing the device, try it. I think you will be impressed. Ed Alt, the designer, knows more about spurious RFI getting back to the RX than practically everyone around, on par with Dean Pappas. The man designs electronic systems for the DOD.

As far as safety goes, arming-disarming and fail safe set-up of the CDI via the radio, is much safer than getting to a switch by hand on the plane. Consider what happened to me last year, where the thottle link became disconnected. I simply shut the thing down remotely rather than have to run out a tank or take a chance landing at high idle. Which is more dangerous?

I fly with a group. I don't hesitate using mine. The risk is lower with it in my view than without it. And BTW-I've been flying RC since 1969...I think I know what I'm talking about too