I don't know if this will help anyone but I have been been running the BTT filament sensor for a few months ago with the below settings. Besides for a few false faults while printing with some clearish filament it's been working great!
M591 D0 P7 C"e0_stop" S1 R80:120 L6.2 E18.6
M591 D0
Pulse-type filament monitor on pin e0stop, enabled, sensitivity 6.200mm/pulse, allowed movement 80% to 120%, check every 18.6mm, measured sensitivity 6.252mm/pulse, measured minimum 96%, maximum 102% over 33984.9mm