The only single wiper system that I've seen that worked as well as two wipers was the Mercedes system. The blade wipes one side, then returns to the vertical position, then moves down vertically a couple of inches, then wipes the other side of the winshield. The system is really complex compared to a regular two wiper system, and it actually looks rather stupid when it is on. I would say leave your two wipers, they do a good job, and they don't look that bad.
Just my .02
