Bump for anyone looking for Extreme Neutral density
I actually just sold mine and bought a B+W 10 stop. The extra stop makes a big difference. For example, you get an exposure of 256 seconds in the early morning with the 9 stop, if you use a 10 stop you get a 512 second exposure.
Hoya 9 stop is HMC (Hoya Multi Coated)
B+W is not Multi coated but you get an extra stop.
Personally the extra stop is more important to me than the Multi coating.