I'll take your word for it. We're still undecided on the filesystem issue, but it looks like IPv6 support still hasn't landed in OAFS, and I rather not reintroduce IPv4 back into our BIND instance. We're going to glue the sysops heads together somepoint this month and discuss it more indepth.
As for cron and kerberos, keytabs are a wonderful thing; we use kerberosized SSH for our cron services so we don't have to deal with SSH authorized_keys madness (we have a backported OpenSSH on the server which can pop a key from LDAP which we use for staff gaining access to the network and for the SSH proxy), but kerberos allows us to have one central list of authentication. We've got master/slave KDCs setup, and BIND is replicated, though we haven't tested failover (yet). LDAP isn't, mostly because slapd is a fucking pig to setup (they threw out a perfectly sane config file for putting everything in LDAP and then poorly documented it to boot!), but all the services are using local accounts so the site itself will stay up if LDAP takes a shit on us.
As for our IPv4 only service, you'll have to wait and see. Trust me, I think you'll approve of this (and I plan to write patches to bring it to IPv6 sooner or later)