Side note: Tried out Soul Mastery instead of Energy Mastery on my brute on Beta. My end bar went dry before I was even a 1/4 of the way through a pylon.
Now I could run Cardiac instead of Musculature but that sounds like a pretty big damage hit when the goal is more damage.
There's also a nasty pause in the followup, focus, gloom, repeat chain that would have to be filled by slash, and with fu, focus, gloom, slash, fu will only be doublestacked.
So there's another nasty hit to DPS.
Seems to me that sticking with fu, focus, slash, repeat with energy/body mastery backing it up is still the way to go for single target on any claws build.