Hi Rubie! My take: it depends–a “lighter” app might be great as it requires less effort in integrating, deploying and probably maintaining, but in the long run could be costly if it underserves the needs of the users (ie does not have enough features). Bigger, more mature projects like PHPBB are great in that they incorporate everything but the kitchen sink, but are “heavy” in terms of deployment and perhaps maintenance (ie a larger project has wider adoption, potentially larger user base, but has possibly more surface area for attack from hackers–but perhaps may have regular patches that can negate this threat). The best guide, more than a matrix, is to ask and analyze the requirements of the user (ie use cases). You can use that as your guide in making a decision.

I chose SMF. It’s light and response faster than PHPBB!