I go double-bladed (and reload the game until I get them as rewards) because, first, I want as much damage as possible (and upgrade my sabers with direct damage components), second, I want it early, when I build my first saber, third, I want all Jedi in my party to wield lightsabers, and fourth, I don't have enough crystals to fill all of them. I don't have Kreia in the party unless I have to, and when returning to Onderon, I give her Freedon Nadd's lightsaber. (Because of her "neutrality", an orange one suits her best anyway.)