BuddyPress.org

afaik with bp multi network users are shared over all subsites and see http://wpmututorials.com/news/new-features/multiple-buddypress-social-networks/

Ron says:
September 8, 2011 at 11:19 am
“Also be aware that in WP (and BP) there is only one set of users across the entire install.”

@ultimateuser userbase is separate by default but super admin and blog admins can invite users from other blogs and last time I checked it out, there’s a function posted in BuddyDev forums where you can have the same userbase across the network if you want it that way, OR allow the users to choose which subsite/s they want to join by using http://buddydev.com/buddypress/introducing-join-blog-widget-for-wordpress-multisite/

@ultimateuser – Ron’s BP Multi Network plugin works with WP Multi Network or their Networks+ plugin, but a third option to create networks is Networks for WordPress which is similar to WP Multi Networks but was last updated more recently in May 2012 – https://wordpress.org/extend/plugins/networks-for-wordpress/

I just upgraded to BP 1.6 and found that I can’t post activity status updates on a private network anymore using BuddyDev’s BuddyPress Multi Network plugin http://buddydev.com/buddypress/introducing-buddypress-multi-network-plugin-create-multiple-separate-social-networks-on-a-single-buddypress-install/ , but maybe it’s me. I might check out Ron’s plugin again to see how it does with BP 1.6

What did you end up using?