Rankink what surface are you racing on?
The local auto-x area in Vancouver really rips
into the tires. More so than ashphalt or tarmac.
We race on a kind of agragate (not sure the right name).
Anyways, it is a very grippy and rough surface.
Superhero, I chose the MX's because they are quite superior to the 712's. Wet and dry grip are both great. They are more comparable with the Falken Azenis. They are however a fair bit more expensive than the 712's. I am currently using 225/50R16 and I love them. I paid around 200CAD per tire which included mounting and balancing. (Around 800 total with taxes and mounting/balancing and installation).