Separation (left to right) is excellent on both. However, I think you're trying to get to sound stage--the 3D imaging of the music/sound. If so, a good open can, like the Senn, will almost always have the advantage. Closed cans generally give you much better isolation from outside noise and don't leak any/much of what you're listening to wherever you are.
Thanks, but I dont need a huge sound stage on these. I've decided on the Shures for the purpose I'm using them for, I know I'll be happy! Thanks for all the help.