I own a 910XT. I have noticed that synchronizing heart rate zones/user profile only seem to work one way (from Garmin Connect ---> Watch). If I change heart rate zones on the watch a whole range of settings file are sent and transferred to garmin connect, but values are not updated on the Training Zones page (http://connect.garmin.com/settings/zones)
F.ex I am referring to settings file for running mode;
C:\Users\HenningKnut\AppData\Roaming\Garmin\Devices\3842729776\Sports\1-1328-ANTFS-3-1.FIT
which is transferred by Ant agent to Garmin Connect, but not updated.