I buy mine directly from Microplane, and wouldn't give them up for anything. They may not be "traditional," but they are wonderful tools. I still use traditional rasps and files, but for fast removal of material, these can't be beat. You do have to be careful, because they can be a bit TOO efficient at taking off wood. For final shaping, I prefer a nice rasp to keep from taking off too much.
I too have noticed that the harder you press, the less material you seem to remove.
David L