Yes, the PSC2 offer better grip. Further, since you own a CS, it is really worth it to go with the PSC2 since that's the tire that the CS was designed around. I still don't understand why BMW USA decided to shod the CS in the US with the PSS instead of the PSC2 like everywhere else in the workd.
I got to compare the difference between new PSS and PSC2 first hand and the difference is quite noticible. When I received my M4cs, it was mistakenly delivered with PSS, so I got to drive it on the PSS for about a week before they swapped out to the PSC2. When cold, there is not much difference in grip, however when the PSC2 warm up, the improved grip is quite noticible. Further, the PSC2 are quite stiffer and offer a sharper response.
I also got to experience the PSC2 in the wet and they left me very impressed. We had one track day with moderate to heavy rain and the PSC2 performed flawlessly. I had heard so many bad things about the PSC2 in the wet, I now know from personal experience that it simply isn't true. Since I already have a dedicated set of tires and wheels for the track, I was considering swapping the PSC2 for PS4S as I need a good DD and wet track setup. But after my wet track experience the PSC2, I decided to stick with them.
The PSC2 however does not like cold weather, especially if it is cold AND wet. As a DD tire, they just don't warm up in cold weather and struggle to grip. It's now getting cooler here in Montreal at 3~12degC and I have to be much more careful with the throttle. If it is cold and wet, I have to be very gentle with throttle: I've gotten wheelspin in 7th at 75mph
. They are still driveable though, but you do need to adjust your driving. Winter tires are coming on in about three weeks anyhow
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As for launching the car, I've never had issues using Launch Control as long as the tires are clean and properly warmed up and that the launch surface is decently clean. For quick stop light getaways, I do a small prob of the throttle to get the DCT to engage the clutch and I then quickly roll on the throttle. This gives me a quick smooth launch and I've rarely lost stop light drag races using it
. If you just aggressively go full throttle from rest, you engage "burn out mode", where the engines revs will rise almost to redline before the DCT dumps the clutch.