Albino Lobo also has 6 ATB bars for a Ravager, and has been very very good for me, despite giving him very mediocre infusions. I'm planning to do a Blue Chocobo for my final Ravager slot for Colosseum battles and such. Pre-DLC Blue is supposed to be, hands-down, the best Ravager monster. If he's hands down better than Lobo, which is really strong, I can't see Lightning being a whole lot better.
Chichu has 6 ATB bars as a Commando, and he's incredible. It's easy to break 1.1-1.2k STR with him (I have 1116 and I did -not- use all Power while leveling him, and again have mediocre infusions. Even 1300+ should be np with proper infusion, and using all Power upgrades, as opposed to mixing in Potent or Vitality.)
If you're only interested in the DLC for the potential new allies, I wouldn't bother. If you want a chance for a new high-level fight, snap it up.