Are the BMW bikes nicked licensed Whyte designs?
AFAIK the BMW suspension is more or less their Telelever design which in turn is the Hossack design as used on the Britten – one of the most astonishing motorbikes ever IMO.
Anyway, the idea is that the braking forces are concentrated horizontally backwards into the frame, therefore preventing the forks from diving and also allowing a pretty constant steering geometry; what’s more the suspension can move freely whilst braking. The system rides very well and rewards a smooth style on a motorbike, not sure how that translates to MTB though.