[Bob Katz]

I have a partial answer. The speed of the external drive is CRITICAL. I purchased a Buffalo 500 Gigabyte SSD with integral usb. It’s physically bigger than a flash drive but ideally faster than one. It awkwardly hangs off the IPhone usb c connector with a USB A to C adapter. They claim “up to 600 MBps”. In my single recording (5 minutes) so far with the drive formatted as EXFAT it seems to have passed recording Pro Res without glitches or error reports from camera. I still can’t believe a Samsung T9 did not pass the test.