The eMember has a separate membership database which has some advantages. For example we can add more membership fields for member’s profile down the road (I have some plan around it) without being restricted by wordpress’s user database. Also when you share a table with WordPress it is highly likely that the plugin will break as soon as wordpress makes some changes to their user table structure. we do have plans to make it so somehow you can configure it to make your members a subscriber status on your wordpress installation.