The overnight Moscow that Aeroflot operate from Heathrow seems to be popular with Russians who come and visit us, and is often sold out, but very much at the Y class end of things. It's not a long flight but there's a lot of timezone change (3 hours) for the distance, allowing an apparent overnight flight. However when they plan on going straight to work from the flight I wonder how good they feel ..... !
I am sure BA know how to handle landside security, they operate to places a lot more difficult than DME in this respect. Maybe more of a problem would be Russian visas for the nightstop crew, I don't think there is any shortcut for crews, they would all need full Russian multi-entry visas and the rigmarole that goes with that. Any crews of other carriers have experience of this ?