SC can create consistent snapshots even if the LUNS are presented as vSCSI disks (i.e thru the VIOS). I am working with a customer (DB2/AIX/SAP) now and is also testing in my Lab to streamline the process. As part of the Snapshot Creation and Snap Restore process you would execute AIX commands on the Guest LPARS. This can be done thru the PRE/POST SC commands.
You don't need NPIV, using Snap Creator you can do the consistent Backup and Recovery even with vSCSI LUNS. One thing you need to keep in mind is SDU is not supported and is not really required in your case. We provided a solution for customer DB2/AIX/SAP with vSCSI configuration with Snap Creator. Also I have tested this in my Lab.
What kind of issue they are facing with restore. Please send me the details, I can take a look.