Something to note is that you don't need a healer on the east boss Rohash. For the very start of the encounter there was a shadow priest solo. When he was about to do his hurricane the warlcok who had been DPS'ing the north boss went over and the two of them would spend the rest of the fight burning the east boss down. The two of them were able to keep themselves healed fairly nicely, none of my other DPS even had to go to the east platform.
Another tatic we employed was using a Prot Pally and a Holy pally on the north platform. With all of the other DPS on the west. We did not do any swithces for the first ultimate ability. Both the paladins on the north platform simply bubbled and /dance'd with the boss until his blizzard ran out. We of course had to switch for the second ultimate ability, but with out doing the switch this gave a lot of time to DPS the west boss down.