If you plan to do the pro touring thing, I just don't think twin turbos are going to work very well on an autocross(It's a delicate dance) and the HEAT on a road course.
Sure factory cars can do it but they aren't making 1000 hp and they have engineers that get paid a lot of money. I'd pick a super charger if you plan to do the multi event deals. If you desire that straightaway performance and don't care to run road races or be competitve on an autocross, twin turbo makes the most power.