Carey and I have spent some time separately and together trying to get the Sportracs stocked and available, in our sizes, in the US. Hopefully we'll be successful soon, then others can benefit.
I rode behind Stan a LOT in North Carolina last month, and can attest to the Sportrac stickiness. I was sliding, on and over the edge of traction. My tires were squealing and screeching the whole time. Stan was unflappable and I don't think his tires even squealed. Since the roads were smooth I doubt that the IRS versus Swing was even a factor, given that my Spyder has positive-camber limiting straps. We both run front sway bars and Koni front shocks. Stan has a rear bar and Koni rear shocks, I've got adjustable QA1 coilovers and no swaybar.
IMHO, the Sportrac5 is the cheapest STICKY street tire available, that is also a GOOD choice for the street.
The Avon CRZZ and the Vred Sprint classic are the other two choices, but are more costly and wear quicker. I'd say the Avon is probably best for the track.