I tested 3 different ESC with the same motor on my Minipro dyno. One was an entry level Hobbywing, next was a Hobbywing Pro and finally a off brand ESC. They all produced the same acceleration curve. As was mentioned, acceleration doesn't really test anything on a modern ESC that can be compared. Braking is probably one thing you could test.

I think when someone say their new high priced ESC performs better, it's because they just spent a bunch of money and they want to believe it made a difference.

The differences between ESCs are in programming options and as an individual knowing what settings to change.

People are probably asking you to test different ESCs in hopes you'll find something that will give them an advantage. If such an advantage existed, every racer would use that ESC unless they were forced otherwise by sponsorship.