The Davis-Wilson guards have only two straps. They're quite light and comfortable. Although I was concerned that they wouldn't bend right and would slide around on me, they work very well.
http://www.gerrydavis.com/Merchant2/...ct_Code=PR1267
I've got a Donjoy Drytex hinged brace that I used when recovering from knee surgery. I tried my Davis-Wilson on over it and it fits, but feels odd. I don't wear the brace anymore, so I have no idea how well this would work out in a game.