Well, I think there exists a little confusion in this thread - at least for me!
Yes - there is a plugin for ST3 and GH625M - and it works fine for downloading training data from the watch.
Phil's plugin did add some features to Sporttracks (ver. 2) that made it possible to download/edit/upload waypoints from/to the watch. That can also be done in GS-Training Gym - but when you are a ST user, it would be nice to have all the desired funtionality here... - the ST3 has another way of handling plugins than ST2 - and Phil's installation instruction for his plugin, simply was to copy the .dll file to the plugin directory in ST2. However this directory doesn't exist in ST3 - so I can't figure out where to put it...