You are asking for a mid bass driver, but you don't have a way of modeling the micro-enclosure you are proposing? The enclosure is going to dictate every bit of the on and off axis response of whatever driver you choose. You might like to review the following video link once or twice, paying close attention to the response trace as the listening position is changed.
YouTube - Broadcast Yourself.
The door/pod shape and volume has way more to do with what you'll hear than the difference in single 4 and dual 2 ohm coils.