I finally made the swith to IMAP from mbox on the server. I still check all my mail from mutt on the server (via IMAP), but I can now do the same using Mail.app if I choose. Next I need to get SMTP auth happy with postfix, but that looks like a lot of hard work.
This seems to be paying off, but I might decide to move from Mail.app to Entorage. I'd just use mutt on my mac, but openssl won't compile from fink. Bummer.