From a tank's point of view, Heigan hits like a pansy. It's not his melee that's ugly, it's his disease and the threat presented by the flame spouts.
As a general rule of thumb, for phase 1 we have our healers and ranged dps standing on the platform where you first find Heigan as you enter the room. The tank kites Heigan across the floor as necessary while keeping him far enough away from the platform that the ranged folks are in no risk of getting diseased. Done properly, that leaves only the tank and melee dps at risk of taking any real damage in phase 1. Phase 2 damage comes exclusively from the flame spouts, so as long as your melee have had their diseases removed you should be able to get by with simply Renew, CoH, and PoM to top folks up. Obviously, you don't have time to stop and cast anything substantial in phase 2. You're better off remaining 100% mobile and throwing instants than trying to stop for something larger and risk falling behind.
Also, my guild operates on the idea that if we have to choose between losing one person because they can't do that dance and losing 1 person + a healer trying to save them, let one person die and keep the healers for the duration of the fight. I think most guilds feel the same way. Stopping to cast during phase 2 is not an option. The spouts come at about 5 second intervals and it takes about 3 seconds to traverse the distance between spouts. That leaves you 2 seconds tops to stop and heal between waves and a delay of one second means you're dead.