I am curious about the plugin """user syndication""" before

I am curious about the plugin """user syndication""" before I build based off the new knowledge of it's existence... I like the idea of being able to break my site up into different complete installs of wordpress... But... I would like profiles, including activity and comments to all meet... Will the user syndication feed in user comments from a slave site to the master site? I know it works on multisite with the post indexer and such, but what about using 2 installs and the user sync?