Let me just state upfront that I'm pretty upset about this. I upgraded to Garmin Express 3.2.4.0 this week and discovered that it broke my ability to import my workouts into SportTracks. Why? Because for some reason Garmin decided to quit using the .FIT file extension with the new version of Garmin Express. In fact, the workouts it pulls off my 910XT now have no file extension, but are still actually .FIT files that lack the proper extension...thus rendering them basically invisible to all software other than Garmin Connect. The simple fix is to just go in and add the ."FIT" extension to the files...but this is time consuming and most consumers probably won't figure that out.
I cannot think of a single valid reason why Garmin would do this other than to screw with people who use 3rd party software/services in lieu of Garmin Connect. It is a slimy thing to do and seems like a thinly veiled attempt to lock our data down.
I'd love it if someone from Garmin would explain just why they chose to do this.