McGahee is putting up decent yards, but he only has 1 TD, and that was 'before' this Tebow mania. His chances of a TD each weak are LOW.
Dez, he's battled an injury, as well as extra coverage with Austin out. Now that things are coming into place, he's about to show his potential. I could see him and Austin taking turns catching TDs all year. And you know Romo has a couple TDs a week to give.
I don't think you're deep enough at WR to lose Dez. I understand having a huge fall-off after your RB1, I'm in the same boat. I also have Dez. I'd rather hold guys like Tate, Helu, Hardesty, Ridley, Torain, Battle, etc and pray than get rid of Dez though. I'd just stay put and play waivers. Trading requires you to be overstacked at one pos, which I don't think you are.