Definately need full Rakata. After that you need spot on rotation and game play. We were hitting enrage timers in full Rakata.
Pretty much if you lose 1 dps (or anyone for that matter) And you can't get them up immediately, you may as well call it a wipe.
Toth/Zorn is a huge gear/dps check. The hardest in the instance they say. All consumables and Bloodthirst is a must.
Pro Tip: Strategy is everything.