Hi,
"another suggestion would be email for paying members."
We have considered this, and even looked into some email clients (esp. HiveMail), but my partner was a bit worried about the impact on the server. I do not really know much about this but from what I gather HiveMail uses a different protocol than the one he wanted to use (and which was less streneous on the server).
"how have you handled the archive?"
We just manually move posts to a seperate category (which contains a bunch of different forums) once every month or so.
This category is read-only and only accessible by paying members.
Sanuk!