This test covers BLHeli 14.4 on both Atmel and F330/F39X/F840 SiLabs. Unfortunately, So far I haven't been able to get SimonK to work on this motor/prop yet, but I'm still looking for solutions.
This time I tested with a lower KV motor to see how it affected the spread. As predicted the Atmel ESCs closed the gap a bit, but still couldn't quite keep up with their SiLabs cousins. The community was asking for the ZTW Spider 18A, and a donor sent me one of those to test. Also have the Emax Nano 20A, thanks to another friendly donor. We also have the Flycolor Fairy ESCs sent from 65Drones. The biggie is the new UBAD 30A Angry Beast, thanks to Bruce over at UBAD.
For my first test I have decided to use a Cobra 2300kv 2204 motor with an HQ5x4 propeller. This combination is one of the most stressful on ESCs due to the combination of high RPMs and quite high current draw (~20A). This should give a fairly clear picture of the upper limit of switching speeds at 4S. (Eventually I would like to test on a >3000kv ESC, which will push things even higher in terms of RPM, but lacks the current draw to push both simultaneously.) Combining this with the PWM generating code on the Arduino that includes instantaneous throttle jumps from 25% throttle to 100% throttle turns this into a true torture test as a first shot.