Philip,
I definitely don't want you(or anyone else) to do something you don't know how to do or want to do. I only documented what worked for me. By all means if you can make it work another way go for it. The main reason for my update was to highlight the fact that the 920XT is not at fault, even though testing appeared to make it the culprit.
My original advice still stands however for booting into Recovery mode, which is a non-destructive activity, and test making the USB connection with your watch. If it works, and works every time, then you can be assured that you have a software problem on your Apple computer, and not a problem with your watch.