The Lady Luck job is ok by itself, but having all three girls equip it means you get a LOT of extra items. If you would have gotten 1 potion ordinarily you'd get 1x2x2x2=8. If you would've gotten 2 items normally you'd end up with 16. As you can see, you stand to gather a lot of junk. When leveling up, try and be near a store so you can sell when you get 99 of whatever item is dropping from what you're fighting. I also think the money bonus stacks but I don't recall exactly. But I know as a fact the item doubline skill stacks.

There's an optional dungeon, I think it's called the Hive, the enemies drop bombs. Three Lady Lucks means you won't have to worry about running out of explosives.