There are a couple of shortcomings that I think I see: 1. If the clock moves backwards (and an "older" record gets created), it doesn't help. 2. If a duplicat

There are a couple of shortcomings that I think I see: 1. If the clock moves backwards (and an "older" record gets created), it doesn't help. 2. If a duplicate timestamp is created with an id that sorts earlier than one of the other dups (and a user has already synced to the first dup). In both of those cases, the user won't receive the new record. (Yes, neither is probable, but neither is impossible.)