At the moment, I am running four separate installations of wordpress setup as sub domains for one domain: tech, games, movies and lifestyle.
I would very much like to integrate all of them and have one shared user base. However, each of these websites has different admins and I would like to keep it such that each admin is only their site's admin.
Separately, I also have vBulletin setup on a sub-domain and would love to have users merged with wordpress.
So, is MU right for me to do what I want to? Also, if I setup MU to use sub directories instead of subdomains, can I manually add subdomains for my main websites and let the users who register use sub directories?