The problem I've always had with forums is that you have to work to follow the new threads. Email is still the simplest user interface we have. I think the approach we've followed here is to primarily use email (ubiquitous, simple, easy-to-delete-messages) and provide a searchable, threaded archive for other folks who are more inclined -- at least one active poster uses the archive exclusively as her means of reading the list.
The other big problem with a forum-based solution is that this list is VERY active. Last week, for instance, there were 500 posts with 173 nominal threads, only 10 of which had more than 10 postings (one had 81, might be a new record).
173 threads in one week isn't easy to navigate in a forum -- it's pages and pages worth . . .
On the administrative side, it's easy to moderate this list if needed but easier yet to let it free-wheel when it's not needed. Doug has found -- and as the list-mom for several lists myself, I concur -- that a simple default moderation policy until you've proved yourself plus judicious use of the boot button for idiots seems to keep the ecosystem here pretty useful without feeling like you have a boot on your throat.
/jordan