I think this is sorted now. I needed to completely uninstall and reinstall these RPMs:
smeserver-userpanel-0.9-10.noarch.rpm
smeserver-userpanels-1.0-5.noarch.rpm
smeserver-vacation-1.0-12.el4.sme.noarch.rpm
Then it started working - I got the 'User Panel Access' panel, which was not there before. I had a feeling the old smeserver-userpanel-0.9-10.noarch.rpm did not uninstall properly in the upgrade to 7.2, because it was still there (other threads say it should be automatically removed) and when I did remove it, I got script errors. It went back in okay though.
So, anyone know the difference between smeserver-userpanel and smeserver-userpanels? Do I really need both to get the user panel access (aka 'user-manager')?