Thanks for sharing this info. Along with the response time you measured, how do the number of steps an ESC has factor into the final quad control smoothness?
HKSS and Mystery ESC's are good PWM performers for quads too as well as being good I2c modification candidates. The Mystery ESC's have the very friendly quad and tricopter feature of being able to completly disable the LVC.
Quadrocopter and Tricopter Mega Link Index