Tried to reach the search settings admin view but didn't get access. Snooping around led me to a new EPiServer 6 group name setting.
Found that the SearchController in the new Shell.UI has a [Authorize(Roles="CmsAdmins")] attribute. So you need to remember to configure mappings for your admin (and editor) groups inside virtualRoles in episerver.config:
<add name="CmsAdmins" type="EPiServer.Security.MappedRole, EPiServer" roles="WebAdmins, Administrators" mode="Any" /> <add name="CmsEditors" type="EPiServer.Security.MappedRole, EPiServer" roles="WebEditors" mode="Any" />