Hi, just a small idea for hardware improvement:
It´s nice to have a double diode in the signal path to the ESCs with the Arduino on one side of each (for MWC PWM), other side connected all in parallel to have one "calibration channel" feeding all ESCs.
I use BAR43C and it works well with promini/HK blue 10A. No need to un-/replug every single ESC for setup, I just switch my TX from Jeti to 35Mhz and connect a spare RX to this "calibration channel".
Tested with manual setup only as I don´t own a programming card.
Regards,
gompf