How to cope with the 'window of compatibilty' and CVSup

[Clint Olsen]

Recently I did the usual portupgrade and found that my 5.5-STABLE box won't
compile the latest lsof.  So, up until now I haven't had a problem keeping
up with FreeBSD releases.  Now it's starting to become a pain, especially
given that my attempt to upgrade to 6.3-X failed miserably.  If I use
CVSup, what tag should I use to pick a viable contour?  I'd like to keep
the ports as new as possible w/o breaking something.  Are there more
fine-grained tags in the ports collection so I can downgrade one port?
Right now my ports collection is busted because lsof was removed in the
process and every dependency to lsof is generating a stale message for
them.

Thanks,

-Clint