So is it best to totally ignore Aussie French cars, or join up (but not actually participate) and thus prevent misuse of "our" familiar user names.

Are mlb, Pugrambo, Double Chevron et. al. concerned about someone else using "their" aliases - is this "real" identity theft, or just a bit of a laugh?

On balance, I'd prefer not to register, as I don't know how safe it is to give these guys my email address etc. - could be identity theft going on whether you register or they do it for you!