The manti with 2 sockets is a much bigger upgrade than you might think.
It should give you a clear 50k dps increase. And the manti also scales up much nicer with the avarage dmg on the rings and amulet.
And for some speed in farming, I would suggest dropping smoke screen. You already use Gloom, it's overkill. Pick up a bat or a boar.
I prefer the boar, it tanks a lot of mobs, making me proffit more from steady aim.
You might also want a windforce for your scoundrel, they are dirt cheep and the knock-back effect it's awesome when it chain procs (just make sure you get one with 49% knockback)