I'm debating between getting the X6 or the X6hr. I go to the gym a lot and I noticed that the x6hr keeps track of your heart rate as well as altitude and this information is then transmitted to a PC. Will I be able to track my cardio workouts in a gym using the PC software. I would like to keep track of my progress. Is it possible to keep a workout diary using the pc software? Also, I swim a lot, can I use the transmitter in the water? And finally, the advertisement mentions that a extension strap comes with the wristop computer. What is that?