Here are the benefits as I see them:
1. People can sign up immediately. At the moment it appears that the only way to get on the general list is to physically go to a meeting, ask to be added and wait several months. It doesn't seem to me that this would be an effective way of getting people involved.
2. There's an archive.
3. There are a number of features such as polls and a web calendar that might be useful. You can have it automatically send out an email reminder for each meeting, for example.
It's true that it's an external service and that is a drawback. But it's free, has no maintenance costs, and has important features that would be difficult to support internally.
Cheers,
Steve
OSX freeware and shareware: http://www.dekorte.com/downloads.html