I know that this is the subject that everyone seems to love to hate, and I've read many oil threads here already. But the other day I followed this link BMW Service Notes through to this document Summary of Permissible Oils.
Written in 2007, it seems to indicate pretty clearly the viscosities and ratings for various conditions. Of note it says that all opposed twins may use API SF or better with no limit to SH (as it does for wet clutch bikes).
From my prior reading here I believed that I needed to find an SG or SH rating, which I did recently. Why shouldn't I take this document at face value?