I am in Moscow, used to be BMI Focussed, but how have BA.. I am limited to LHR as a BA Route from here, or JAL, CX and Finnair to their hubs.

Lufthansa have many more flights on *A and Aeroflot on ST. I stuck with BA.. Primarily because of the short CW Hop to LHR, Double Tier Points and Lower costs than LHR-Place. I think that is the equation to use. I would suggest you look at earning power and base decision upon whether CX hops and routing via HKG is going to earn significantly more benefits than SG, or visa versa.