As far as I can see there are three types of scuff sheet.
Firstly - the thin horrible fablon like material that just cracks and is pointless.
Secondly - The polyurethane sheets, the ones used on helicopter blades, which a lot of people stock and use and are the ones I prefer to use.
Thirdly - The Hammer Edge style sheet, which is the thicker polycarbonate sheet and one which often has the matted look to it.
Have yet to see any real significant science to back up any claims to improving performance, but from experience they do help longevity.