I see on the features for JoomDoc 4, there is this statement which is obviously a feature planned:

Also individual documents may be owned and worked with by a specific user, group of users, registered users or simply anyone. (coming soon)

Has it been scrapped? I need a way of allowing only individual users access to documents within a folder (a site where people can download personalised Fitness programs for the gym). I know I could create lots of groups with each user being the only member, but that's going to be quite complicated for the end user who will deal with the day to day running of the site.

JoomDoc looked like it was the perfect answer.