That does sound easier/safer than hooking the intercom straight up to the camera.
I may go for the mic/recorder option, as it may well work out at roughly the same price as getting the GoPro skeleton case required to access the mic port, whilst allowing me to record both the ambient noise (GoPro mic) and the coms (mic/recorder combo).
I'll be using a PNR headset, and not one of great quality (loaned from the club, need to save the money for flying now
). I'll see how it goes, but I may end up having to hook the intercom up to the recorder.