I would do that trade. Marshall is so good. I drafted Dez this year but moved him two weeks ao because he is just so frustrating.
It seems you are deep enough at RB that you wont miss Stephen Jackson and he is another player that is inconsistent.
It Head to Head (which I assume this is) I always want guys that produce week in and week out, especially this time of year.
I would worry a little about Cutler not being there, but not enough to stop me from doing this trade.