We actually use only 2 healers in our 10 man group and it has worked very well for every week we've attempted him. We use myself (a disc priest) and a resto shammy. Only frost resist is his totem or a pally aura if we have on available. No one in the raid uses any of the frost resist gear or enchants. Only time we wipe is when kids are not smart enough to step out of the blizzard, which we rarely encounter. Really fun fight though. First 25 man attempt is tonight!