not sure what you mean by sun visors, to me they are the visors above your head in the cab that you swing down to block the sun which come with every vehicle.
The one on the roof makes it look like a taxi or a Ford Transit Connect clone. Not sure it does much for you, mine came with it. The ones on the windows are useful and I like them, always put them on my cars.
oh, okay side window visors, yes I have those too. Don't see the point of the one of the roof as mine already has a built-in air-deflector and I find it works very well. Not sure if the 2011 models are different with their sunroof.