Pray tell, why should "foo.bar" be more `readable' 1.2.3.4??? With a human reader in mind I preferred domain names over IP addresses. This is also a nearer to DNS (I know, I know), you do specify hosts there as servers, not (sets of) IP# .
I would even go further: nameserver information in the domain object is utterly useless and only clogging the database; the ~~~~~~~ We have not yet heard about the idea of publishing unpublished secondaries this way and as I pointed out already it is useful to be able to announce "hidden" primaries. It is also useful to be able to find out the primary server (it is the first in the list), even if it is not "hidden". With proper DNS setup this information should be coded into the SOA RR, but experience shows that this is done wrong often. (OK, I wonder how and why the correct information shall find its way into the DB.)
nameserver information belongs in the nameserver, not in the database: then it's only duplication of information that's not serving any real purpose. So drop the n-server entries!
This should hold for more fields - the dom-net is available in the DNS by RFC1101 style coding, zone-c is coded into the SOA and admin-c and tech-c can then be announced via RP records. Anything left for the domain object ? -Peter