Are you concerned with aerodynamics or something? Otherwise if that isn't your concern, then the existing wheels on your Roubaix should be able to handle any width tire you are able to fit in that frame.
I really don't feel you'll get better support. Though if you are running super low pressures and feeling them roll sideways under you, then you might need to put more air in them.
If you are looking for aero or maybe even aesthetic reasons, then is your Roubaix disc brake or rim brake?