Several years ago, I won an Apple Watch in a giveaway. It was a version 1.0. I tried using the watch in a game, but the issue I had was the touchscreen didn't work in the rain or with sweaty fingers (and unfortunately, I do perspire quite a bit). I gave up the idea of trying to use the watch.
Personal preference for me, but I still like to go "old school" and write down my game information. I use a Garmin watch with the Referee Watch app that essentially mimics a Spintso's timing features and links to the watch's GPS. However, I absolutely see the value and merit behind a program like RefSix. The heat maps provided by RefSix look great. I use a StatSports GPS tracker (my one "toy" that I've indulged in) for heat maps, and they are really good to see where I am covering, how deep I'm getting into the non-AR corner, etc.
That being said, I've heard many good things about RefSix. I love the idea and think it's awesome for those who are a little more forward on their tech than I am. If you are going to use a watch feature, I think RefSix is the way to go. As I've said on other threads like this, pick a system that you like and go with it. You don't want to be thinking about your administrative procedures in the middle of a match. My method is different than your method, which is different from his method, etc. As long as you record match information accurately, do what works for you!