This part sums it up best:
... the ZII is most likely to be highly setup dependent, and will reward precise driving. The Rival, on the other hand, floats all boats higher. It will make "heroes out of zeros", much in the way that the Kumho V710 r-comp did when it first came out, versus the super-precise Hoosier A3S03 of the day. This is especially critical on the track, where one small mistake can have disasterous results. For autocross, in the right hands and with the right setup, the ZII may prove to be faster for the best drivers.
Related 2013 Tire Posts:
Dunlop Direzza ZII - First Driving Impressions
Dunlop Direzza ZII: The Lap Time Comparison We've All Been Waiting for!
Dunlop Star Spec Direzza ZII: A Tire as Exciting as a Date with Scarlet Johansson!
First Dunlop Direzza ZIIs Shipped to Customers!!
Bridgestone RE11A: A New Suspect Has Entered the Crime Scene