I'm very happy to find your plugin- I'm a web developer and our company is looking into solutions for a client that runs a business association website. It looks like your plugin and the memberfindme service are a fantastic solution to our clients' needs!
Two questions- first, are you storing member data from memberfindme in the wordpress db? I'm hoping not as this would allow migration to other platforms/support if the client ever would require it. Second- the client has on their current site a relationship between a "director" (which would be a user in the simplest terms) and a "business sector" in their membership directory. Would there be a fairly straight- ahead way to implement a link between lets say a post or page in WP and a custom category in the directory listings? If your plugin offers some level of shortcode or access to data from the directory listings, I would be able to code in a bit of custom display in a template to allow this to happen and replicate their current functionality.
Any response is greatly appreciated- looks like a fantastic tool!