We finished HM Lost Isles in about an hour and a half learning as we went.

Group Comp

-Assassin Tank = Full Rakata (Augment Chest / MH / Belt / Bracers)

-Merc DPS = Full Rakata

-Marauder DPS = Full Rakata

-Sorcerer Healer = 126 Gear from daily quests

It was an excellent time and the entire group felt challenged, I'd give it a 4/5 in difficulty.

Normal mode is there for a reason. Play the difficulty that suits your group.