Mmmm. Some good sound advice above! No experience with these machines, belts are pretty good these days but vary under load = careful tool path planning and gentle, gentle. Ball screws, depending what you pay for them, can have linearity and repeatibility to microns. There's nothing wrong with a stiff repeatable machine with an accuracy of 0.1, if you know it really is 0.1 steps. My machines a stepper on the z and about 0.1 accuracy as well, tried a pcb but you need to go through to 0.25 - 0.3 to be sure tracks are clean, assuming the bed is in fact flat. The last thing you want is perfect pcb with the top left corner shorting because it's a thou high. Is the 0.1 based on the stepper / mechanical performance. Steppers are good at going to one repeatable point, They don't do the in between bits. And all machines bend a bit under load as do tools! But, as a first thing, you could mill yourself a flat bed to start with which will be at the stepper step, if you see what I mean? With a nice straight edge to align too? If the bed is "flat" but 1/2 a step out then you're accuracy can only ever be 0.15mm? You can cut 0.05 and 0.015 but never 0.1 +- 0.1. Then then beds aligned to the head and your accuracy will leap? I mean 0.1 steps but each step within 0.001 of where it should be and repeatable, I think this is what you need to know from them. You're gona be so pleased when you make you 1st pcb and it works!