I'm about to do oil change on my .. DI v8 4.8 100k km
Spec required A40
Both oils meet the spec... car was always fed M1 0w40
But not sure how I feel about new formula for FS... I have both oils on hand.
It meets A40, that is what you need.
As for BMW, LL-01 is updated and according to some people right now most stringent spec. New M1 FS is almost 0W30 oil. I personally like thicker oils so my preference would be Castrol 0W40.
However, you are asking very political question. You will be fine with both, and if you use M1 0W40 FS you can let us know how did it in engine.