I noticed better shifting (up and down) after changing to M1 LV ATF. Also The color of the fluid stays much pinker than MC atf which turns nearly black after 20-30K. I do a drain and fill every 30-35 K.
I agree that keeping pistons free from ring coking is vital for long engine life, proper performance, and preventing loss in fuel mileage. M1 oils has given my engines that for the last 42 years at 10K OCIs.