I am in a similar situation, setting up a hexa with 30" props (the “NS” ultralight type), U8 Lite L KV95 motors, ALPHA 60A HV V1.2 ESCs at 12S. Take-off weight will be around 18 kg.
Across all these discussions here, I found varying information about the MOT_THST_EXPO to be applied, when using the ALPHA ESCs.
So, what would be a safer way to find out a good matching MOT_THST_EXPO setting beside the hard way (with test flights). For earlier configurations, I built a thrust test stand, but this was driving the motors with PWM directly coming from a microcontroller (Teensy 3.2).
My assumption would be, that if I drive the ESCs from a Pixhawk (Holybro 6x) using RC passthrough on one of the channels, then the MOT_THST_EXPO will already be in the game and the goal would be to find a setting, where the thrust has good linearity to the PWM value, right?