Aha! You're right Cobba - the thing that threw me was the fact that the forks (and the tabs on the rear of the bike) are IS, while the calipers are PM. So, can I just go straight to a PM now? The thing that confuses me is that the adaptor used adds a good deal of thickness to it, so wouldn't it have to have the disc moved?

Cheers!

PS Here's a macro shot, just to make things clearer