Argh! Don't use Bestial Wrath and Rapid Fire at the same time, it's a tremendous waste of the focus generated. If your're blowing all your cooldowns at the start of a fight, that's fine, but use Rapid Fire last, just before you reset with Readiness. Then wait for Rapid Fire to wear off before you use Bestial Wrath again. It will make a difference (not huge, but noticeable) to your dps over the course of the fight.
I tried BM on Elegon last night, Belimawr, it didn't fail as badly as I'd feared. It is still a little sketchy at times though, I still prefer how the cooldowns for SV line up, but BM does compensate a bit if you can line up Kill Command properly, as it does take a massive chunk out of the add's health.