I have the Moto Z Force droid and the Garmin Forerunner 230. SO far the connect app seems to work okay. The only issue I"ve had is sometimes it loses bluetooth connection, but I think it's because once I pair it I turn off location services. When I do that, it randomly loses the connection so I have to re-pair. It hasn't lost connection during a run yet though. *now I just jinxed it.
I get my notifications fine and the syncing works well.
I think the bluetooth/location services has more to do with Android 6.0 in general than the phone because I had the same issue with my LG G3 on Android 6.0