I think they could drop Sixaxis, it never added anything to any game I played (even games that used it have an option to turn it off >.>). Dualshock support though needs to be there, and I think they realize this since the eventually added it in the ps3 controller, even though they them selves said it couldn't co-exist with Sixaxis.
And I have fairly large hands and have to agree that the pad fits comfortably, though do wish that it was stretched horizontally a little bit.