If they used the actual number of bass hits Cam Fleury does in TERRORHORSE's "Packet Flier" the song would actually be impossible to play! Its already in my opinion the hardest drum song ever in rock band!
I'm no expert on the matter, but this appears to be double bass:
The Legend of the Rent is Way Hardcore
I can't imagine that there are too many kicks left out of that charting (although there may be).
i'm gonna get my roommate to play a 3rd kick on my next waste track so we can just go ahead and usher in expert++ mode.
Expert + songs could be fun, but without the support from HMX it can't be done. I don't feel like I'm missing anything though. It would just have been an added bonus.
I already have enough difficulty with the bass in a lot of the metal songs.
On a side note, I read somewhere that 75% of RB users play on medium? I find that hard to believe as 9 out of 10 players in quick play do play on expert. The other 1 plays on hard.