How do you move a large multisite to a new URL?

I need to move a WP multisite + Buddypress site with around 1400 blogs and 800 users from “subdomain.mysite.edu/subdirectory/” to simply “subdomain.mysite.edu/”. Basically I need to get rid of the subdirectory. What would you recommend? I’ve read up on moving WP installations (http://codex.wordpress.org/Moving_WordPress#Moving_WordPress_Multisite) but I want make sure I’m taking the most sensible approach. Thanks!