You can import all users with all xprofile fields to your BuddyPress installation.
This plugin will automatically activate all user accounts and send notification as selected by the admin at the time of import.
It currently works with WordPressMU + BuddyPress installation.
If you have any issue with this plugin, need help, or have any suggestions, You may contact me at http://manojkumar.org or www.futurescape.in.