A little late on this thread, but I think you would be fine - except for the heavy loading as you mentioned. Essentially it's simply support of the material and of no consequence if the torch passes overhead. I've got slats on mine, 1/8"x2" I can flip them over and end for end so I can get a lot of life out of them. I also think one reason people "bend" or put them in some stress is to keep the stock from "quivering" on straight slats while the gantry is jumping around.