It seems you may have a R1200 paperweight soon. It may be 35mm long, or it may be 500mm long. I'd suggest borrowing a stem to test for a while first. I had a 40mm paperweight as well, it is now in the co-op pool of components that a few mates and I have that serves as a second life for components (tyres, saddles, stems etc) that we didn't like, but someone else wants to try out without committing. You are worried about unweighting the front wheel, but when front wheel traction matters, you shouldn't be in the saddle, and your standing riding position will very quickly adapt to the new position. Or you will realise that it isn't lekker and that the 50mm sweet spot is really sweet.
