BuddyPress.org

I have ~250 users and quite a few blogs, and my database is still below 50 mb. We’ve only been active for a few weeks though. Extrapolating wildly, I’d say a reasonably active 100 user installation would take a month to build up 50 mb and that is three months to build up to your limit, 150 mb.

So in the short run, it is sufficient, but after a while you’ll have to move or sweep out old stuff from your database.