Most of us carry a tire plugging kit because who wants to get a tow to a dealer to get a tire plugged, if you can do it yourself. Unfortunately, because there is no way to bypass the immobilizer, if the antenna fails, carrying a spare makes sense because it will take less than 3 minutes to get the bike started again.
I'm riding heading south next month and out west in the summer and I'd hate to be stuck because of it.. and with my usual good luck, the failure were it to occur, it would be on a Saturday afternoon in an area where dealers are closed on Monday, so I'd be stuck till at least Tuesday. I think I got my spare one for $115. It's a lot cheaper than a tow or a motel room.
ADV decals, patches & flag? Here