I've been playing with the notch filter some more, it seems it could be very useful for the buzzing prop thing. Right now I've settled on a 140/175hz dterm + 140/210hz gyro notch, it seems to be a good balance between noise-reduction and flight performance for this quad.
Here's some guides to get started.
https://github.com/betaflight/betaflight/wiki/BetaFlight-3.0#how-to-obtain-data-to-evaluate-noise-frequency-for-setting-the-notch-filter
http://www.propwashed.com/notch-filter-practical-guide/
http://www.rcgroups.com/forums/showpost.php?p=35467947&postcount=35885
http://www.rcgroups.com/forums/showpost.php?p=35471939&postcount=35942
Betaflight 3.0.0 RC7
Motolab Cyclone
Aikon 30A SEMF
EMAX RS2205 2300KV
AKA Robogenesis
