Hey there all, I will contribute with what little I know and what I have seen around the paddock.
Traditionally it has all being DZ03G and RE11S, now since A050 superseded A048 it being popular, this is what I have seen around the paddock in recent race meetings. I think A050 is a control tyre for the E30's. People say A050 lasts a bit longer in longer races before going off and withstand more heat cycles. Both Bridgestone and Dunlop man said it goes in cycles and A050's is the flavour of the month. Bridgestone, Dunlop and Yokohama will outrun Nitto's, Toyo's, Kumho and Hankook, hence you only see the former 3 at race meetings.
Sitting in dummy grid, I look across the grid, many are now on A050, prior being on RE11S. DZ03G is still an old favourite.
Graeme, we have been running our bog standard 156 on just high performance road tyres, not R's. The RE002 had chunks taken out on the outer shoulder. The Direzza D1 were fantastic until someone stole one wheel. Can't afford R's for the 156, not needed for what we are doing with it, just for fun, plus there is no power to do anything, I sip on my macchiato while going up the straight.
The 156 has had mixed mechanic issues this year, but that's what happens running an old and unknown road car which I also use as a daily. So a bit more maintenance and checking to go in.
My 2 bob.