I have tested a few different ESC's for throttle response time, that is, the time from full throttle given to the ESC gives full motor power.
Note that the test starts a low throttle (running motor), not zero, so the start up delay is not included.
This scope screenshot shows a turnigy plush 30a ESC's response to a instaneous increase in throttle from low to full. (1.1 to 2 mS at 50Hz PPM)
Red trace: motor current.
Yellow trace: PPM signal
A doubling in PPM frequency halves the ESC's response time, thus makes it possible to use higher gain, and therefore making the quad more stable.
This ESC and most other I have tested uses a finite response low pass filter based on the PPM frequency, on the throttle.
The filter has 7 steps at the biggest difference in the throttle, less at smaller differences.
Tested ESCs response time at 50Hz:
Unknown #1 (99% sure it is a Jeti Advance 8A, according to the owner):
Notes: very good
Turnigy Plush 30A
Turnigy Plush 10A
Turnigy Plush 6A
Turnigy K-Force 40A:
Slow Brain 20A:
Notes: Response time is constant regardless of PPM frequency. Uses a constant time base for the filter, not the PPM frequency.
Otter BS 40A:
Notes: Also filters high to low throttle
I will update the list as I get my hands on more ESC's