Assuming you can start 3 RBs, I would skip this deal. I understand your desire to upgrade WR, and I do think Colston will start producing, but I would prefer greater RB depth. This is especially true with undefined injury to Hillis, also I don't trust LT to stay healthy. Also, I have a feeling Wallace is going to come on strong with Big Ben. Otherwise, you might be able to buy-lower on Colston.
The reason I'm trying to unload Forte is because I don't trust him to produce at the rate he did last game. Other than Week 5, Forte has been producing under 3 YPC, which carried through all of last year. I feel like he's a sell-high candidate at the moment and have been actively shopping him around. I've made trade offers for several WR1s, including Jennings, Johnson, Nicks, and Wayne, not expecting anyone except maybe Jennings to bite the bait. I agree that Wallace is bound to break out with Big Ben in the picture, but I'm in a 3 WR, 2 RB, 1 Flex league and could use a back up WR, Colston and Jennings being the biggest buy-lows at the moment.
I agree that you need to trade for a wr, im just not sure if colston is the one. You would think hes bound to come around but brees isnt as great this year and still spreads it a ton. Theoretically the passing game will open up once pt and bush are back. I dont know why jennings doesnt have more catches. Im not sure who else you could get for forte.
You have to make this deal. You have a lot of RB depth and not any at all with WRs. Despite the depth issue I even think on paper it's a pretty decent deal. You're not ripping yourself off or anything. Colston is still a solid WR and should start to do better.