too late to change to security branch?

[Bill Stwalley]

I have servers running 6.1 and 6.2.  I use freebsd-update in cron jobs to
install binary security update to the base system, and use cvsup/portupgrade
in cron jobs to install port updates.  By default, cvsup uses CURRENT
branch.

I am tired of some updates breaking something unnecessarily, and am thinking
of changing to SECURITY branch in cvsup.  Is that possible?  Some of my
ports are already locally compiled with customized options.

If that's impossible, can I wait until the release of 6.3, upgrading to it,
and then switch to SECURITY branch in cvsup?

If those are entirely impossible, can I switch to STABLE branch?

I'm confused by this system, please let me know if anything I do doesn't
make sense.

Best, Bill