I run 16 inch Kuhmo 712's on my WRX for autocrossing/street use right now until I wear them out. Then I am upgrading to 17's for the street and getting some victoracers for the stock wheels. I have done 5 autocrosses this year with the 712's 5+ runs each, and one being a 2 1/2 minute road course. Of course you will have wear, but not terrible. I still have plenty of tread left. Just keep up the pressure on them when auto-xing, and rotate them frequently. I am about to flip the tires on the wheels also, so I have more tread on the outside again.
The 712's are the not the best, but are sticky enough for getting your experience up.