Well, I "fixed" it...not
I switched to primary FlightAware feeds dump1090-fa + dump978-fa and have the other feeds read network (beast-tcp) from these
The stats speak for themselves. They are all pretty much inline except RadarBox is showing at best only about half of what all others report
Point in time snapshot:
FlightAware: Total Aircraft = 76 With Positions = 57
FlightRadar24: Aircraft Tracked: 90, Aircraft Uploaded = 68
Adsbexchange: Total Aircraft = 72, On Screen = 56
RadarBox: Flight List / Map Total = 28
So it seems to be a systemic problem with RB