I think we're getting the blue steel kanetaka and the iwasaki mixed up. At least some of iwasaki's steels have swedish steel and some have White II.

White #1 and White #2 are very close to what tamahagane would be if it was perfect, except their carbon content and quality is a lot more consistent and they are a lot easier to produce. The best tamahagane should still be better for keeness if it is in the same hardness level and carbon content, though.

I think the influx of swedish and english steels in the early 1900s was pretty instructive, but it may have been more of a cost issue than anything else. In the tool world, some of the english steels bring the next highest price to tools that have genuine tamahagane for their cutting edges, but So mentioned in several places (I don't know if on his website, but I think on Harrelson Stanley's) that tamahagane was overrated in woodworking tools. Razors get less adhesive and abrasive wear, though, so the comparison might be different.

I still haven't seen anything definitive about tamahagane - how it holds up in durability or how absolutely sharp it gets compared to white #1 and #2, or assab K steels, I'm wondering if you didn't tell people what was in a razor if they could tell the difference. In woodworking tools, there were gobs of tools labeled Tamahagane that just had mass produced carbon steel in them. I don't think iwasaki would do that, but he may be forge purifying steels to take things out of them and make them more like tamahagane.

The finest steels made in the US and england in the crucible steel process were probably as good or better than tamahagane, and the legendary status of the japanese swords is attributable more to the construction methods than the steel, at least in relative terms to western swords.

I'm as guilty as anyone for spending money, though, but I do wonder if I could tell the differnence between the stuff I spent a lot on vs. the mass-produced vintage US steel or the yasugi steels.