the machine is very similar to mine except they are driving it from under or at the side of the table using belts. Not sure about the gantry, I think it will twist easily especially if you decide to hang a heavier router or spindle on it later (and you will, believe me). Have a look at my build, it would be easy to adapt the gantry design to this table and it would be so much stiffer. You don't have to go to ballscrews, it would be just as easy to use belts if you want to keep the cost down. I've never understood why they need to drive the gantry from so low down. Mine is driven by rack and pinion from above the table by a single stepper driving both sides just below the supported rails holding the gantry. It works really well and because the drive is almost in the same plane as the supported rail, there is much less strain on the drive train/bearings.

Jeff.