I've heard the ZIIs aren't much different than the Z1s. I'm still quite sure that the RS3s > all for warm, dry grip. I think they increased the UTOQ to 200 so you can run them in Chump car now as well. Not sure if that has any affect on your auto-xing.
The downer with the RS3s is they are noisy, not so good wet grip, terrible in cold weather.
2013 F30 328i - Melbourne Red
2011 E90 M3 - Monte Carlo Blue
2004 E46 M3 - Imola red