Thanks Dean. Given what you've just said I'll stick with the stepper on the front of the Z and see how it goes. It wouldn't be the end of the world to move it to the back to get better performance if it's needed.

I've started pricing the parts up, it's looking like the build will come in around the £2000 mark. I'll put the pricing spreadsheet up somewhere once I've finished filling it in as it might be useful to people trying to decide if they can afford a build.