Don't hesitate to say it open way. Do you mean vBulletin? We think, miniBB is a completely different software... vBulletin has been created for one purpose, miniBB - for another. If you check Showcase
section, you'll see there is a board with more than 2 million messages
, and it's running on miniBB. Number of messages is not the real thing we're worrying about now :-) It more depends on your hardware, else software, to handle such kind of activity.
It's only up to you, what you finally choose. You see around what miniBB is, you can play with it on our test site
... make the right choice corresponding to your needs.