...
SAML attributes are supported and can be mapped to their Name as an OID easily, they also appear in the RequestedAttributes in the SP generated metadata. You will need to map a SAML attribute to the SIS ID attribute in the service, this appears to be a key field used in manual provisioning, it appears to treat these values case sensitively in SAML, but not with other plugins such as LDAP, that can cause some issues during a migration.