Known caveats:
Still using names instead of UUIDs. Means nothing in the short term but eventually, if this is not changed, if a shop owner changes their name they will lose control of their shop. (Serves 'em right, right?) But an admin can fix it for them using the set owner command. Also, if someone changed their name to a shop owner's previous name before their shop is fixed, they would be able to take over the shop. This is a great way to identify people you should ban.
Also, Locked Chest was replaced with Stained Glass, so any locked chests in shops will be converted into stained glass. Nothing I can do since Mojang reused the ID.