Got mine set on BB time and has been accurate since the day I got it. Havent tried network to see if there is a difference.
I've had mine on BB Time since my post above, and it still drifts off. Selecting "Update Time" brings it back into sync for a while.
The time displayed on the Date/Time screen is live . . . watch it for a minute and verify that the "Time" and "Network Time" click over at the same time. I bet it doesn't . . . however, if you select "Update Time," they get synced. Unfortuntately, though, only temporarily.