I actually have an Arccos unit...
Bottomline, unlike Game Golf where it requires you to tag the club before you hit the shot, the Arccos system has wireless sensors in the plug (the plug goes into the butt end of each club and is synched via bluetooth to your phone) that can tell when you're making a practice swing or hitting the ball. It tracks your entire round, gives you distances, etc., without having to press a button. Only drawback I've found is that you have to have your phone on you at all times so it registers with the club, and sometimes it doesn't pick up gimme putts inside a couple feet so you have to add it manually which takes 5 seconds. Other issue is the battery drain. I can make it through a round no problem, but if I want to check scores and run the system it can become an issue, as you'd expect.