You didn't really ask for my opinion, but this is UKGSer, so I'll just go in with both size-12s, as is the norm here
...
On the balance of probabilities and me being somewhat risk-averse in this respect (bike cutting out when I need the engine, not liking the idea of sitting on the kerb 100s of miles from home and the fact that the broken wire and intermittent electrical signal *seems to* have contributed to the ECU failure in Glenn.1's case), I'd try to fix it, or at least understand it better. I'd be starting with making sure no other RFID keys are near my bike key , then shoogling the wires (inspecting the loom at known weak point), and then progressing to swapping RingAntenna with a known-good (or new) one. It is a few hours of work and 30-odd quid in total. If you were in Scotland, I'd lend you my spare RA (if the part # matches) to try. Another inmate may help you there if you find one nearer to you.
Good luck mate.