As far as I can tell, if we set <useshibboleth>1</useshibboleth> in koha-conf.xml, this will show the "Log in using a Shibboleth account" link in both staff and OPAC. But we have a setup where we want Shibboleth only for staff, not for patrons. We can hide the link in the OPAC with JS or CSS, but having the option to remove the link completely would be better.