If you were to take this trade (which I'll get into in a bit) you would then have to drop either HOU or CHI DEF so that you can pick up a 3rd QB, because you currently don't have a backup, though I'm assuming that you'd use the pick he wants on a QB.
The upgrade from Dalton to Schaub is huge, especially this being a 2QB league. However, you already have a deep WR rotation in Bowe/Brown/Lloyd/Garcon(who I like this year) and a rookie sleeper in Jeffery. You can't have Dez or Julio, and I agree that I wouldn't want Miles either. I'm not really high on DJax, and barring injury I don't see him really cracking your starting rotation, since on a normal week you would start Foster/CJ at RB, with Mathews at the WR/RB spot. I would also want to get a 4th legitimate RB to play for injuries/byes, or else you're starting McCluster (yuck). That's why Benson has great value for your team. You won't start him but maybe 5 weeks, but those 5 weeks you''ll be damn glad you have him.
Anyways, that leaves 2 WR spots starting and a WR/TE, and I would have Bowe/Lloyd at WR with Brown at WR/TE, or Garcon for byes/injuries/matchups. SO if you do the trade, I only see one real option for WR...Kenny Britt. He is the only of the WRs available to you that would, when healthy, contribute to your overall starting roster. In just about all formats he was a top 10 WR throughout the first 3 week. I think he gets 2 games max as a suspension, which means if he stays healthy he can play for 13 weeks. Big if though. Then you could try and make a couple trades and get that 4th RB to help you during those weeks when you can't start your big 3.
Because of the huge upgrade you get at QB2 (which is a larger factor than some may consider), and you gain a potential top 10 WR, I would make the deal. You'll miss Benson a few weeks, and taking Britt is a huge gamble, but I would lean towards doing this trade, dropping a DEF so that you can pick up a 3rd QB. Then try and get a 4th RB (drop McCluster). Hell, those weeks that you can't start all 3 RBs, you could start RB1/RB2, then go with WRs at the WR1/WR2, WR/TE, and WR/RB. So you could actually use all 4 of those stud WRs that you'd have (considering Britt a stud here)
I'm in a similar situation with Kenny Britt actually. I have the luxury of the offer remaining until we hear on the suspension though. viewtopic.php?f=18&t=516884