I have a Garmin 60csx (with the latest 2.60 firmware loaded) and I just installed Topofusion 2.81. I tried the real time tracking and it didn't work. I had the 60csx connected to my PC via usb cable, and had a good position lock (inside my house!). I set the GPS type to "Garmin" and "usb" and hit "start tracking" and got an error message saying "Error initializing COM port, check for other programs using port." I've tried this several times, disconnecting the GPSr and reconnecting it, with no luck.
From what I've read in Groundspeak, the new "x" series units are having a lot of trouble communicating via usb with various programs. It won't work with Google Earth, for example. It also won't work with USAPhotomaps, or DeLorme Topo USA 5. It wouldn't even work with Garmin's own nRoute until the latest firmware upgrade. After the firmware upgrade to 2.60, the unit will show a current position in nRoute, but trying that with Delorme Topo or USAPhotomaps will crash the programs.
Also, one slightly annoying thing that happened when I installed 2.81 was that it reset the colors on all my tracks to red. I had previously set them to different colors, and had to go into each and reset the color.