Should be noted that any server running 1709 cannot be added to S2D pools as it stands currently since it's not considered production ready....
Correct. S2D is gone from non-GA WS2016.
Storage Spaces Direct
Storage Spaces Direct is not included in Windows Server, version 1709. If you call Enable-ClusterStorageSpacesDirect or its alias Enable-ClusterS2D, on a server running Windows Server, version 1709, you will receive an error with the message "The requested operation is not supported". It is also not supported to introduce servers running Windows Server, version 1709 into a Windows Server 2016 Storage Spaces Direct deployment.