Hmm, something nice about this change log solution is that merge is built in by design. You could very happily default to all new collection items start with a UUID despite things like user definable item names.

Normally this might be annoying but with merge as a first class citizen its easy to add a "merge these items" feature. Not only is there no hidden data loss, but it also adds the nifty feature of being able to merge totally unique item.