I would be skeptical. Any tiny piece of grit that gets between a caster and a floor will cause scratches. We have sliders on the bottoms of our kitchen stools, but the hardwood floor in that area has gotten scratched anyway over a period of 5 years. The scratches are many fewer and much lighter than if we didn't have the sliders, of course.
Also, I think a lot depends on which hardwood the floors are made of and what finish was used on them. We have a relatively soft hardwood floor with a very light-duty finish (not my choice!). If you have a harder wood then it won't scratch or dent as easily, and if you have a couple of coats of polyurethane on the hardwood then it's just the polyurethane that gets scratched and that's pretty easily fixable. I think the safest way to go is with a large rug (with cushioning underneath to protect the floor from the rug).