I agree that $1100 for a used Trek 520 is too much, but I'm a bit of a cheap skate. I think that in the last 2 or 3 years that the over all quality of the 2 bikes is comparable, the Randonee might even be a little better (things like leather bar wrap).
If you are willing to wait for the 20% sale, I think that the Randonee is a better deal. Also, if you have an REI credit card you will get an extra 5% in dividends, which lowers the cost another $50 or so.