I've tried this on a few systems.
First the upgrade failed becuase the zones are on a SAN file system.
So I commented out the SAN disks in vfstab and tried again
Second time the upgrade failed becuase it could not upgrade the zones.
Tried upgrading another system
First the upgrade failed with zones installed
Was able to uninstall and delete the zones
Did and upgrade and it worked perfectly
Then recreated the zones
Tried upgrading 2 other systems
First the upgrade failed with zones installed
Was able to uninstall but didn't delete the zone configurations
Did and upgrade and it worked perfectly
Then recreated the zones and had a problem because some packages were not installed.
Did a pkginstall of SUNWluzones SUNWlur SUNWluu SUNWzoner SUNWzoneu and this allowed me to recreate the zones
all this and you can't use a ZFS file system for a zone.