This is what I've found while tanking this boss...if the healer sucks we are going to wipe! I'm sure that's the case with most FP's but it is especially so with this one. Every time I've wiped it's been because of a bad healer. Bad DPS on this means the dps will die.
I wouldn't even say holding threat is an issue even with the adds. It's very distracting especially when you have dps running toward you with a bubble following them and drop it right behind you but I can adjust for that. I cannot adjust for a healer not dropping heals at the right time. I had a healer (commando) who waited until I was about 30% health before dropping a heal and by then it was too late. I've had under-geared Healers try to run it and we wiped. In fact I ran it last monday and wiped 3 times. I didn't run it again until later in the week.
The healing on this really makes a difference from the tanking perspective. I'm sure a healer will say the same about the tank as well but I've tanked this successfully too many times to know it's not an issue holding aggro for me.
Honestly, a bad healer can make nearly any fight next to impossible, but this one isn't very healing intensive at all as long as everyone is doing what they are supposed to (e.g. Staying behind the boss, moving the lightning, interrupting incinerate). Most of the wipes I see on this fight are due to dps dropping lightning balls on the tank, and the tank not knowing how to compensate and start kiting. While kiting, I've also seen a dps drop lighting infront of the tank, and trapping the group. Really the only issues a healer might be having for this fight are Los problems, or incinerate being left too long and hitting the melees as well. I don't know about commandos and sages, but a smugglers cleanse is on a 6 second cool down, so if three people are hit by incinerate, the healer is going to have a rough time.
The soft enrage on this one can be damn near impossible to deal with as wel unless you have a well coordinated group, but in my experience, a well coordinated group doesn't usually hit the enrage timer.