My fiancee's 38mm SG sport had a chip on the screen. After some back and forth with customer service, we finally got a manager to ship a replacement out. That's out for delivery today. We dropped the bad one off at FedEx last night.
I hope the replacement is a full watch. No one told us anything about just sending back the face.
Do you have AppleCare? Apple is trying to make me get AppleCare before they will ship a replacement without receiving mine first. I really don't like the idea of sending mine out, waiting for them to receive, then shipping me back a replacement - I might just wait until the Genius Bars have stock to get mine replaced instead.