I toured 1700 miles on an SU200 this summer, and it was good. But for my commuter I bought an SU100. It was easier to find a rack without the disk brakes of the 200, plus it was cheaper and I like the flat silver color of the 100 better. Also, the 2007 Su100 and 200 come with super nice leather saddles -- way better than the cheapo one they came with in 2006.
I recommend it to you if you really want the disk brakes, but if not the SU100 is just as good.