I used the BT45's on my old GPZ500 and found they were a cracking lightweight tyre. The front started to deform once it was close to needing replacement and that threw up a few bar wobbles. Apart from that they were fine, and wore well. Probably better than the Sirac's are doing to be honest.
I scanned evilbay and found no xt-x wheels gonna have to wait on that one, or see if the FZR wheels in the shed fit