I just purchased a Forerunner 405 and noticed that it appears in Basecamp under the "My Garmin Devices" section. What determines which devices appear there? My Edge 500 has never shown up nor did my FR60.
My guess is firmware and unite design determines what mounts. If you right click the forerunner and get info BaseCamp tells you what transfers functions are available, for example weather you can delete previously stored data.
