I agree with you, apples to oranges
Doing scientific tests is hard, test and tune days exist with shorter simple courses and skidpads to reduce variables, 28 feels good to me and is reflected in consistent times that I'm happy with. Lower and I find the tire less predictable causing errors, higher and I feel that I'm losing lateral grip, unfortunately I did not have good Accel data to support that only the stopwatch. I've also spoken with people I respect with similar setups and we've arrived at similar results.
Edit: approx -4 and -2.3 camber here iirc, been awhile since I've been on a rack.