I think .030" kerf, which amounts to a .015" corner radius is going to be plenty acceptable. I also suspect that with the thin material you want to cut, that might be able to be customized down even smaller. As for the consumption of the garnet, not sure that's going to be a big cost, first, it's usually not that expensive (at least not in blasting media) and from the pictures of the Omax unit, they appear to have an abrasive cup that isn't very large looking. I'm sure they can do a test cut and give you a breakdown of operating costs, garnet, electricity, does it use normal water or de-ionized? All of that should be something the sale man can get you info on.