very good discussion!
BTW: For me it's a little bit strange to see people posting for Akismet which have been posting against other blacklists in past very often. Sorry, for this tiny off-topic. Okay, now back to this discussion.
For the very good Contact Board Administration MOD IMO only one feature is missing: Different recipients for different subjects or tasks.
1. Block spam posts and spam user account registrations done by spambots and human spammers!!!
with blacklists. Redirect the very rare false positives to the contact page.
2. Protect the contact page with CAPTCHAs (or with another good different feature(s)).
If a contact page would been added to phpBB core so then please add an impress page, too!