Hi
There's not a lot of difference between Pro S and R, mainly it's viscosity, but there is also a slight difference in the blend and Pro R has a different level of friction modifiers making it suitable for the wet clutches in bikes as well as cars.
I wouldn't say the Edge 5w-40 has a higher level of additives, but it has different ones. The Edge TD is aimed at fairly standard cars that have manufacturer specs to meet, such as the VW505.01, but the Pro S is aimed at high performance applications (although it's unofficially suitable as a replacement for VW505.01 oils, it's what Guy uses in his Seat with a PD engine). The additives in the Pro S are there to keep it as stable as possible at higher temps, as well as performing their normal duties. Manufacturers don't like to give out much info about their oils, as then rivals can use it to their advantage, so I can only pass on what I know.
Cheers
Tim