IIRC, 4min 30 for the enrage.
This said, as a Juggernaut, we had it the 5th try we did it in HM (first time for 3 of us, the healer gave us a rundown but he did it in normal mode)
The main problem for the tank is interrupting the Incinerate. Even if the first tick applies, the attack must be cut and the dot cured. Maybe it's my imagination, but it seemed to me the largest part of the damage done by the incinerate dot was on the last tick. Anyway, it must be cleansed. In case of a mistake, another player must cut incinerate when the channeling starts.
Btw, it's a cone with a short range, you only have to check melee players position.
Ignoring the arc lightning is fine, it's manageable.
The rest of the group doesn't need to move far from each lightning dome, if there's enough space left on the lane, just stay at the limit. It'll be less tedious as the number of domes is restricted. Around 7, I think, after that the older disappear as soon as another come in
For the adds, their damage is negligible. Just ask for an aoe if the group is moving, but if not, they have to stay on the boss. The tank will get the aggro and kill the add. If necessary, there's between 14 to 20 seconds between each Incinerate, so he can switch his target
The 4th time, we had the boss to 4%, but his enrage/overload killed us. After that, the group completely ignored the adds if they weren't moving, I was the only one to kill them. L5R was down before any enrage. No dome spam, no mad chaingunning, no lava everywhere, no unwanted adds
All of us were half columi, half rakata.
Something that can help, when the boss uses his chaingun attack on the whole group : the single or, if not, the pbaoe taunt can still be applied. Even if ignored, it'll still reduce the damage by 30%. This can be used on any boss ignoring the tank. Even with a protection, the pbaoe taunt is still able to be applied at least for the damage reduction
In the end, I like it. It's the first time I need to be so focused, as there's little room for errors. Yeah, it's harder, but it was advertised as is. The only nerfs I would see on it is, as said, a reduced radius for the lightning domes, while being sure they aren't spammed on the same place, especially for melee dps. And maybe, increasing a little the incinerate recharge time. Actually, without TS or mumble, cutting the wrong power will end with the tank death.
ps : sorry for the mistakes, english isn't my native language.