Having built a few machines now and used several different hardware store solutions for the slides, I would say that the number 1 consideration is rigidity.
This being said, the easiest way to make a rigid machine is to make a small machine. Drawer slides can work OK on a moving table if the travel is kept small enough. Drawer slides on the Z axis do not work well at all though, another solution is necessary there.
Also a moving table design with a fixed gantry will be far more rigid than a moving gantry design.
So, if I may suggest, lets work towards a small (8" X 12" travel??) fixed gantry moving table design.
Colin