A 10sp cassette will also fit on a Shimano 9sp hub.

IRD now has an 11-30 and a 12-30 10sp cassette (along with their 11-32 and 11-34), you may want to consider. However, the 11-32 and 11-34 has not been getting good reviews because of rough shifting. I have not seen a review of the 11-30 and the 12-30 but they may shift better with the smaller jumps between gears.