First In. No question. Slugs got a juicy PvE buff, making them viable DPS options when you can get close. First In with Vorpal will tear massive chunks of health out of yellow bars. It even slaps in Gambit where yellow bars and invaders with roaming supers are a common sight. Lightweight shotguns were never that amazing to begin with. The damage you put out often isn't worth the amount of ammo the gun eats through. Couple that with the fact that Trench Barrel requires constant setup and pellet spread makes your damage inconsistent? Xenoclast is the loser here unless all you care about is cleaning up weak trash mobs, and even then, there's better options. If you want to use a good lightweight frame, get yourself a Seventh Seraph and go nuts with Warmind Cells.