Thanks for the clarification. This was very much just about maximising the possibility of an op-up, rather than expecting one. It definitely seems like the best idea is to just use the BA status to access the first class benefits on the ground, which I think would be valued more than being treated differently by the cabin crew on board.

Looking at the priority that CX adopts, and having myself been upgraded J-->F on 4 of my last 8 sectors between Europe and Hong Kong in the last 7 months, I can only conclude that I have been EXTREMELY lucky!