GP4S are black chili and supposedly just as puncture resistant as Gatorskins.
This is what always attracts people to the GP4S and the Conti site features a Black Chili logo but the description is:
Black “Max Grip Silica” compound optimised for wet weather adhesion, low temperatures and extended tread life
They certainly feel different to GP4000SII for example and the description for this tyre is more blatantly Black Chili
The legendary GP4000S tyre has been updated to include a broader range of sizes which now also benefit from the latest cutting edge rubber compounding available in the bicycle tyre industry – BLACKCHILI….
…..Advanced Black Chili compound for an even faster, safer ride
There isn’t a great deal between the Gatorskins and GP4S in use for me. Both are pretty puncture resistant but quite harsh and not particularly nice to ride in the grand scheme of other tyres… but it isn’t a surprising price for the puncture resistance which is usually more important in the real world. Speed/ resistance-wise, the Gatorskins come out at 19.3W, GP4S are 17.2W and GP4000SII 12.2 so there is a bit of a gap from either to a *proper* race tyre (again not much of an issue to most of us in the real world).
Best advice would be to go with whichever is on offer and buy the biggest size that fits your frame (they come up a bit small IMO and small doesn’t help the harsh feel) 😀