I could write a book about what's missing or clumsily realized in the various membership and member-list plug-ins.
In addition to customizable membership/subscription levels, capacities, and management, I needed a searchable public list of a potentially large number of members at different levels. The list had to be linked to unique, secure, easily user-maintainable public member profiles different from (but overlapping with) WP user profiles, and not bring the members into the normal WP back end.
In my research I ran across numerous developers and designers struggling to cobble something similar together. It's the kind of implementation that social, political, governmental, educational, professional, etc., organizations might find useful. In other words, it's for a site where membership itself - not the same as "community" or "content" or "items" - is the "product" being "sold."
No single plug-in did it all or integrated smoothly and simply with the ones that filled particular gaps. I could, for instance, have tried to integrate BuddyPress and S2Member, but would have had to hack away a ton of front- and backend BuddyPress stuff completely irrelevant to my purposes, then newly construct the main capacities.
So I decided to build up to the minimum I needed and add to it instead, and eventually realized that for my site the "search" and "search results" are more important than the "list" part. In fact, in the hacked version of your plug-in that I'm using, though it's only a first-phase minimum implementation, the "list" doesn't appear at all except when a search for a member name happens to turn up multiple results.
Well, like I said, I could write a book on it. I presume that a lot of organizations of the type I mentioned, if they're of sufficient size, would be using or developing enterprise solutions within some other framework entirely.