I'm now thinking more along the lines of a Super X2 from Arc Euro. Shipping to France might be expensive but it looks to be much more substantial than the X1 variants. Where do you get 12mm ball screws? The smallest I've seen are 16mm. I might start with the existing acme and make my own anti-backlash nuts but will need a ballscrew for the Z axis.

I bought a cheap 4-way driver and steppers off Fleabay before finding this site and reading the comments here. It seems to work OK with Mach 3 and EMC2 so fingers crossed. I'll put the driver in a box with a b....y great fan.

Thanks for your comments,
Russell.