Fitz has looked really good, so that's my first thought. However, Cassel has the best matchups of any of these guys from now through week 13, but he has tough matchups (check out this tool: http://fantasynews.cbssports.com/fantas ... up-tracker
) in 14 - 16 (probably the playoffs). Fitz and Henne have the best matchups in 14 - 16.
I think Cassel has been fairly consistent (with a couple sub-par weeks). While Fitz has been a little better, I think Cassel's favorable matchups put him over the top.
I think you'd be in decent shape either way, and better off than going with the trade.
Thanks for the help on mine.