I would not have traded a Model 13 for an XD.
A model 13 with a 4" barrel and Pachmayr grips is nothing special. They are on GB all of the time and don't bring much more than what I got out of mine (I made a couple of bucks over what I paid for it on the trade). They are like model 10s - a dime a dozen. That being said, I probably will not be trading away my RB model 13 with a 3" barrel any time soon.