It is coming of age with the latest firmware update. You can now turn off automatic recalculation. This should ensure that routes created in Mapsource are not changed when loaded on the gps - a key feature for many people who plan motorcycle routes in Mapsource.
I was quoting the guy on the advrider forum there, Boyd, but I'm glad to hear they are straightening everything up with firmware/software updates. As I said, I plan to replace my Gramin 276C with this one one day, but 276C is still going strong (except for the buttons getting somewhat sticky again) and I know the drill on it very well by now.