Hey Pianoscott,
Unfortunately, I don't have a great answer for you about how much longer it will be before we have the ability to add other users to your account.
Moz has been working really hard to improve the current toolset, both backend data collectors as well as many UI improvements. This has meant that we were not able to focus on adding multi-seat. However, now that many of these updates have been released, we are prioritizing new feature improvements such adding another user to your account. We are still in the preliminary stages of planning, and we do not have an ETA. We're sorry that we haven't gotten this out sooner, and we promise to keep everyone informed.
I highly recommend that you subscribe to this forum, where you can give your feedback directly to our product team and get a notification whenever the post is updated: https://seomoz.zendesk.com/entries/20199538-Is-there-a-way-I-could-add-another-user-to-access-my-PRO-account-
I hope this information is helpful. Please let us know if you have any other questions.
Chiaryn