I finally fitted the B&M μ (mu) that I bought 5 months ago. I was hesitant to drill the mudguard but in the end it was a piece of cake.
My wiring follows the brake outer along the top tube, then spirals down the seat stay and back up the mudguard stay. Looks ok.
If I have more clearance in the future I would consider having the wiring on the underside of the mudguard but right now I cba with over thinking that.
The electrical connection is temporary so I will update that at some point.
Placement is at the highest point on the mudguard that still allows fitment of the rear rack.
The light is bright, the stand light works perfectly and it’s tiny. I should have purchased a silver one but hey ho, if I had a silver one I’d want a black one.