Would you make this trade?

Your QBs aren't too weak- Warner will start doing better. Just be patient there. I think your weakness is at RB. I'd try to trade for one of his RBs instead. The trade you mentioned is good for you, but I doubt he would accept it. Harvin has high value right now after a few good weeks, so try to deal him for a better RB. Just my opinion. Best of luck.