I don't wanna pop the bubble for such minor issue, so I will just say not to rank this yet. The HP Drain in the hardest diff is 4, which is quite bad for an Insane. This is the only thing I could find in the set, gonna talk to grumd when he's up.
Actually if you try to play it, you'll see that in slower parts HP Bar almost never touches the maximum. The drain is pretty high and missing a slider or two lowers the HP down to half or even more. The reason is that kiai parts are just full of streams with no breaks, they contain really much of 1/8 repeaters, that all raises the HP Drain very much.
The map plays fine even with HP7 (just testplayed it, even missed some of the 1/8s on purpose and didn't fail). I also played with HR (HP7) with misses and didn't fail. It's a fact that the hp bar is not full, but this means nothing. If you play the map bad then you fail, that's how it works. HP Drain no less than 6 would be appropriate here, though 7 works too but it's your pick.