The stinger looks like it's rack and pinion drive on all axes. They say that for the stinger 2 and it has the same rapid speeds. In their gallery, you can see the R&P on the y axis.
I've got a router built from 80/20 and cncrouterparts.com parts (what the FLA kits use). It works pretty well and there are tons of people using these parts on the diy wood router forum here. The main thing I'd be concerned with is the lack of shielding on the linear bearings. There's no wiper like on a THK-style linear bearing and you can screw up the bearings because of that if you let debris pile up on the rails.
CNC mill build thread: http://www.cnczone.com/forums/vertical_mill_lathe_project_log/110305-gantry_mill.html