Update. I have been in contact with my Motorrad dealer about the noise from the engine. I also sent them a copy of the BMW notice. They have no knowledge of this notice before now and have been in contact with BMW Motorrad UK about it and are awaiting further information from them. Hopefully next week.
The dealer thinks it could warrant an investigation and inspection of the affected parts but they are not aware of a modified part number for the rocker arm, so thinks that if there is any premature wear in the arms, they would have to be replaced with the old type rocker arms.
I will update further when I know more.