One is silly and nonsensical and the other is something 1625 builds.
Adam, the 6wsd turns easier than a 4wsd is the same reason that a 6wd turns better than a 4wd. However, all of this goes out the window when you turn your wheels so they are perpendicular to the long side of your chasis. I'm not sure how it would behave then.
Edit: answered my own question. You can't turn while strafing along the short axis of your bot assuming the the wheels are L/R steered and L/R driven.
http://i.imgur.com/95CrP.jpg