I would agree that ball screws are over kill. Another factor to consider is the extremely dirty enviroment drive components operate in. Rack and pinions are much more forgiving than ball screws. In addition a 10' table with dual X drives would not be practical for ball screws. Perhaps they are more suited to a 2 X 2 like the Torchmate? [nomedia="http://www.youtube.com/watch?v=X4vy5as5ksk&feature=related"]YouTube - DSCF1144.AVI[/nomedia]
The majority of industrial table builders I have seen are using rack and pinion. A few incorporate a belt drive system with their tables. I have included a link to a company called Retro Plasma. They build industrial plasma tables. You can zoom in for some closeup pics of all their tables in the PDF pictures they provide for each model. They do make some nice machines.
MINI HORNET HD CNC plasma and oxyfuel cutting machine
This company uses a belt drive on the X axis and a rack and pinion on the Y.