You have to respect the elegance and ingenuity of Walter's solution, but though I personally love it, I find his adapter to be well kinda.... Well..... ugly on the bike.
In itself off the bike it's beautiful, on the bike not so much as it doesn't match, looks small and stuck on. A 10 for it's direct simplicity and effectiveness, 6 for aesthetics as they simply do not match the aesthetics of the engine.
That said.... If I was going to go that route, I'd use his connection at the head but then I'd take the original exhaust port nut, cut the threaded portion off weld in some metal on each side between the fins and drill it to match his attachment flange.
I know everyone can't weld aluminum like I can but you should be able to find a shop that can do this.
Essentially you could still use his clamp at the head, but couple it to a finned flange that works the same way but matches the original exhaust nut configuration.
It' would be like a custom BMW version of a the old KZ Kawa exhaust clamp.
Or essentially like this one I just Photoshopped:
Easy enough to make and it would match the other side.