Multisite or not multisite, there is the doubt

Gerardo Inactive
Just Getting Started

I have seen many pages about multisite, all of them full of pros and cons, so I would like to tell you about my project and understand what is best for me.
I have this site (site1) full of notices, users and also a buddypress install.
I will have this other site (site2) which will take some notices of site1 and also will allow users of site1 to enter.
I will have this web application which will use Wordpress protection to allow access.
Is multisite for me?
what other options I have to share information between sites?
Thanks a lot for the help.