I haven't used the Binsui, but hear that it does well but only with a nagura (not a big deal in my book; there's a video of Maxim using one and, yes, he starts of with a nagura, a nice big Botan). Meanwhile, the Ikarashi is supposed to have better feel, but is a bit more expensive (if you go by JNS prices) and a smaller stone; the JNS verson also has very rounded edges, further reducing the sharpening surface, and you will also need to flatten it out when you get it (though the flattening is easy enough). You don't need a nagura to use it, but it's still helpful (I'll usually use a diamond nagura). Aside from on JNS, the same kind of Ikarashi is available in Japan (I've seen it sold online for a higher price) and others which haven't been filed down on the edges like the JNS version and are cheaper, though I have no idea about the quality. Anyway, probably not much difference, so go for: Binsui for price and size, or Ikarashi for performance. Or just get both and sell the one you find you use less.