I can say that having used both weapons quite a large amount; HBS is definitely better than Katana. I felt this way even before the Katana's "nerf" (I believe it was a nerf, the main factor that made Katana a good weapon was the speed). Now that HBS is faster, longer, has a better stab and is significantly cheaper while having a slightly weaker swing, I argue that it is quite a lot better than the Katana. They are both good weapons but comparatively the Katana could use some form of buff.
That being said, Katana was primarily used by Weaboos and roleplayers beforehand and it will always be this way; people crave aesthetics.
On a side note, I don't find the HBS model in any way attractive. I have a masterwork and I use Finalboss' heirloom pack but I find the Longsword much more attractive than the HBS, that being said the HBS is better for my build.