I work at a CDP and we are updating our integration with Maropost.
Normally we would batch the subscribers to be updated, but there doesn't seem to be method for this in the API. We can have thousands of subscriber updates per day. Without an automated bulk update method we are making a discrete API call for each subscriber update.
If there isn't a method that doesn't require human intervention for a bulk import of subscribers, I suggest an endpoint be available for bulk uploads of subscribers.