Hi Richard - not sure if you are still looking, or if you have taken the plunge by now !
We have a PFM 750 machine with a four axis BZT controller. It's running a bespoke cutting head for our product and has worked well for the last couple of years. We are contemplating buying another for the next development project !
You should check that they are going to put an isolating breakout board in the controller, I was disapointed that ours didn't have one. We had a load of issues gettign ours going with a compaq deskpro PC, and it turned out to be down to the on board parallel port. Adding a cheap card into the PC made all the issues go away ! I've since built a second lab based development machine (nothing to do with CNC!) with an optically isolated BOB, and that worked a treat right from the go.
Only trouble you might find is that I can't raise a response from BZT right now.....