With regard to personal email collections, in
generally I don’t save copies of email messages that I know
are retained in an online archive.
Exactly! Do many subscribers really have their own personal copy of
the list archive sitting in their email account?
My biggest problem with going private is the primitive search
capabilities of Listserv. If an alternate mechanism existed for
searching the archive, that would help. But I think I'd still vote
for an "open" archive rather than a private one (though I'm not
strongly opinionated on the issue aside from wishing the archive was
more easily navigable).