Glad to hear it's up and running! In regards to Dovecot, etc. -- I faced much the same. I wound up going with many of the same packages I'd used on IRIX to make it easier to retain configuration settings and databases - Cyrus IMAP, ncftpd, ircd-hybrid, ipfilter, Postfix etc. Still took a while to get everything set up and configured, but not nearly as long as working from a clean slate
The event with the outage last week probably makes it sound like the D510MO is to blame, but it was really just a hard drive that quit while still well under factory warranty. The drive has already been shipped off for a free RMA. Aside from that drive (which failed quite loudly - clack! clack! clack!) I haven't had a single crash, freeze or unexplainable event occur since starting the FreeBSD server last January. I'm quite happy with the setup so far.