In my experience, yes. You would lose toeside edge control (slower edge to edge, harder to turn) because your toes are too far away from the edge to exert direct force.
I find that boards that are too wide feel a LOT stiffer than they actually are, so I tend to ride softer boards in order to compensate for a wider waist (I have tiny feet, so all boards are too wide for me).
You could ride the Roundhouse of course, it would just fee more like a door than a snowboard. Beautiful deck though.