3 day events for sure ! 7 min quals seem fine, If you can make 10 mins use it to your advantage in the finals.
I do like the idea of control tires however with so many manufactures it would be to hard to keep everyone happy.
Maybe a different brand for every state title and open for nationals ? e.g QLD - vp pro, NSW- proline, WA - aka, SA - losi ?
All the importers will get there turn as well as the sponsored drivers.
Personally i have cut down the bigger gas meets because of cost and time away from work/uni with the 4+ day meets, however if its cut down to 3 days i will definatley be able to go to a few more.

ScottyK