Im level 45. yeah the 45 damage smg isnt that great, but the blast and ammo regen is sweet.
iv also got a good shock, corrosive and fire smgs. lol. i still run with phoenix mostly, with spark and inner glow and diva. iv got catalyst for +25% cooldown/etcetc iv been running same class mod forawhile for that xp% bonus and +2 rare item find and +3 phoenix/intuition/diva.
i have higher damage smgs, but i dont go for just high damage. i try to avoid scopes and i go for elementals. i think the double anarchy im running is 56 damage. but that's x4 so it really chews them up. altho it eats my ammo so fast. even that general knox trap i ran out of ammo solo and had to resort to sniping him and shotgunning.
gettingmoney i think those missions are all story related... if you just do the main story missions and beat krom/etc vault keys the claptraps should lower the bridge for ya. check out new haven and helena pierce etc.