I would never consider using Laser Rifle over the Flamethrower though, for the Firebat. I mean, seriously. Laser Rifle is a polar opposite of Flamethrower. When it comes down to it, The Barret is just a Heavier Punch on the M45 with increased consumption, it could almost be seen as a strict upgrade. Don't ever argue weight of items. The move speed impact of weight is hardly noticable, and frankly, isn't a big deal considering you can just unequip a weapon and walk.