Ya know Ian, you keep mentioning the chain breaker, however I don't recall anybody's chain failing 'em around here on their BA/SM. Seems to me these new stout O and X-ring babies are just that..."stout".
I mean, yeah, I suppose it's anyways a good idea to be prepared and all, especially if we're talkin' about an older bike like your Triumph Chopper(or say any older bike with a kickstarter and breaker-points

), but like I said, I haven't heard of anybody around here having their chain fail on these newer babies....a whole lot o' chain GUARDS maybe, but no chains.
(...though maybe you have, eh?!)