Nope, it does make a difference like the Sigmas. From Tyll's review:
"With normal speaker listening, the wavefront is hitting the side of your head and ears at an angle. To mimic this geometry, Sennheiser mounts the HD 800 drivers slightly forward of your ears, and slightly angled back towards them. The larger diameter and angled geometry of the HD 800 driver produces a wavefront that arrives at the ears in a more natural way than with traditional headphones and allows more of the normal reflections at the outer ear to occur, which allows the brain to understand and localize the sound it's hearing significantly better. The result is significantly improved imaging."
So true! I was the one who screwed up because I took the pic from the wrong side!