Running an IBEC defeats any isolation. IBECs are not isolated, they are just switched regulators. Any issue in the ignition will feed right back into the receiver. Their filtering is only good when when the ignition is operating properly, a bad capacitor, transformer arc, etc will take your plane down.
In my opinion, you would be better off running a smartfly sport reg and having redundant batteries to the receiver with regulated power, then use an IBEC off of the receiver to run the ignition. This way you have the redundancy to bothe receiver and ignition as well as noise filtering and optical cutoff from your transmitter.