Live track works well basically but it is not usable because the email notification triggered in the GCM app is only send about 3 hours later that the ride starts. Most rides have already finished by then.
Sadly it is impossible (at least I don't know how) to find the live tracking without the notification.
With group track I can see that the tracking has started but most of the time waling around with a 2nd edge to see where my partner is (if I'm not on the bike myself) is not convenient.