Chimera has been awful for forever. Microing the pet so it actually hits the group has always been a huge pain in my ass. God forbid you are burning down the blade lords, and you hit the breath just a second after he charges somewhere and your chimera is off holding its dick out in the middle of nowhere breathing on your hpally.
I'd personally run BM / Worm. Switching hunter to main after this tier, but one of our tanks brought his hunter in as survival with AOE talents. He wasn't overly geared but I had him switch to BM/Worm for the burst. I know SV has decent single target but BM is one of (if not the) best burst specs for this fight. With so many CDs to burn through on the +600% phase he drops like a rock and BM Dps skyrockets. He's 483ilevel and although below the rest of the in total his damage to WL was incredibly good.