Since you have to buy two rasps to get the same cutting surfaces as the Nicholson, I see the cost thing different.
Also they are not tapered. The radius you get is fixed. I am not sure where I would use that one radius. They are very sharp, very grabby, they just want to cut. That said I ordered two flat ones. I don't see much use for the "1/2 round" ones, I'll just put them away for a rainy day.
I also got a big 12" 8-grain Auriou cabinet rasp. It finishes like 40 grit sandpaper. The cut is much slower than I expected, no faster than 40 grit sandpaper. It requires much more pressure than the Iwasaki's to cut. I like the hoof rasps better. I probably should have bought the 10" 6 grain.
Both brands of rasps are high quality tools. They are just not what I needed. I am buying tools blind and that is no way to do it. I need hold somethign like this before I buy. There are no retailers of decent wood working tools near me. Maybe a hundred miles away, but traffic is so horrible that I stay home if at all possible. Unfortunatley the culture and interests out here, have changed. People simply do not have any interest in hobbies. Thus there are no stores where I can shop.