I was running SC3 on the rear at pitt earlier this season, had some gnarly tearing on only the left side of the tire. MDM recommended I drop the rear pressure by 3 or so Lbs, and man what a difference. Evened out very well. This is my First year on slicks, and I'm hooked as well. switched to a SC2 after the 3 wore out. having this much grip on a 2 i cant imagine what a 1 or 0 must feel like.
There's definite grip difference in the compounds, for sure! I am not an official Pirelli tire guy, but this is my two cents from personal experience. I wouldn't recommend a SC0 to anyone unless they were at the least mid pack Advanced group and racing. The only time I'd run a 0 at a track day would be if it was a race take off and I was just burning through my used tire stack. Even then, I'd probably keep it for race practice and use either a 1 or 2. I do 2 sprints (12-18 laps) per SC0 on my ZX10, then they get bumped down to practice tire status. When you start talking about tire life in laps, not days...you're entering serious grip territory. I also found I had to change my line and suspension a tad bit with the SC0, as it gripped so good, it would drive my R6 straight out of the corner, whereas I was used to being able to slightly spin up the SC1 which would help get the bike turned.
NCBIKE is particularly hard on SC2's in the summer. You'll actually get better wear out of a SC1 on the rear in June/July/Aug than a SC2 there. This isn't always a constant for every track though, because we've had GREAT wear out of the SC2's for endurance racing when some events were very hot.
Figuring out what compounds work best at what time of the year, per given track, takes a long time to figure out and until you figure it out for you and your bike, it's always best to refer to the tire vendor the day of.
Front compound all-out grip is the same between the 1 and 2. I've never been a fan of the SC1 front and always prefer to run the 2 up front. Biggest difference between them is feel. Some like the 1, some like the 2. A lot of it is rider style/preference, and some of it is bike setup.