I agree that Courier-IMAP's documentation is lacking, but it does support Maildir and SSL -- do the others?
It took some time, but I got Courier-IMAP-SSL installed and running, and I'm using omail (omail.omnis.ch
) for webmail -- it supports Maildir, and it reads e-mail directly off the HDD, not over IMAP.
While my IMAP server isn't under a heavy load (it's just me and my family/friends), Courier has been solid, requiring no intervention.