No, I wouldn't make this move... you are in 1st place... you want to win this year.
This move is one that is looking towards next year. Too many fantasy managers make moves that look too much to the future and it hurts them in the present.
I would keep Benn for playoffs and then look at moving him in the off season. move him for a 2nd round pick in the off season and you are further ahead than accepting this trade.