Interesting debate.
Having studied the ADS-B lat/lon encoding/decoding algorithm extensively in connection with SBS-1 position issues, I'm interested in the "official" AirNav view re setting RadarBox home position.
In the SBS case, airborne positions are rarely, if ever, affected by changing the home position, whereas ground positions DO use the home location as part of the decoding process (documented in the manual). The ground position encoding is based on a 90nm grid, so if your position is out by just a few miles you're probably OK as long as aircraft aren't on the other side of a grid boundary from your home location. The further out you are, the more likely you are to get positions decoded incorrectly.
Is this the same with RadarBox? Cosmoc's experience would suggest that it is.