The XP thing was a guess, based on what I had seen with a mismatched level player pairing.
As far as loot goes, I find the loot tables fairly crap, especially when solo. Fair enough in a group situation you should get a chance at looting whatever equipment any of the classes present can use, but when my Sith Warrior is by himself and is looting sniper rifles and scatterguns, it really annoys the hell out of me. As for commendations, that's another system I think has issues. A nice idea in principle, but none of the commendation vendors have enough decent gear worth buying. Some might have one decent item, like a belt, gloves or helmet, but that's it. Coupled with that is the fact that you can no longer trade in one type of commendation for another. Subsequently I have hundreds of commendations across all planets that are essentially useless. Probably should just use them to buy credit boxes to turn them to cash.