I have run the SO-2 on my car for the last two years with very good results. My first set lasted for 10,000 miles on the rears and 15,000 on the fronts which included five track days. They offer a very predictable feel, good feedback, and IMO a great looking tire as well. One of the things I appreciate about the design of the SO-2 is the rim protector that is built into the sidewall of the front tires. I run a set of high polished HRE 547 wheels and it's nice to know I have that extra measure of protection "just in case". No curb shots yet!<knock on wood>
I am now running a set of S0-3's. I only have about 650 miles on them so it's difficult to provide a true evaluation on them yet. I can say this, I ran them at Sebring a couple of weekends ago, when they had about 300 miles on them, and the feel made me miss my SO-2's! I recognize that with only 300 miles on them the "squirm" I felt during directional transitions might be discounted to simple tread block movement due to the newness and full depth of the tread. They are a good looking tire but they do not have the same rim protector that the 2's provide. The jury is still out on the 3's.