Can't speak to the EVO version, but I've run the original S20's on my Pani (190/55 rear) and liked them. Good tires; neutral, fast warmup, better in the cool & wet than the OEM Pirelli's. Not as much raw grip or temp resistance as the Pirelli's if you're doing track time, but absolutely plenty for the street, even ridden aggressively. They made some changes to the EVO to stiffen the front casing and changed the center compound to improve wear on the back, but I wouldn't hesitate to use them if I were looking for an alternative tire for the road.
Yturan makes a good point about the new RS10 though; it's a step sportier than the S20 and looks to be positioned more equally to the Pirelli SP (max dry grip, with less emphasis on wet and wear). I actually have a set inbound, so they'll be my next tire.