The issue I've had with MagSafe2 is that it's very sensitive to vertical force: If there is any tension at all on the cable and I rotate my rMBP more than 15 degrees or so around the axis between my head and the screen (say, while using it on the couch), the connector disengages. Not so if it's rotated around the vertical axis. It's not clear to me that there's any safety or durability justification for this difference, only that they wanted a connector that was much thinner along one dimension than the other.