My "local" radio store has some Flexradios on demo and they seem nice. But I'm not sure whether I should get a used Flexradio such as a 3000 or 5000, or should I go wholehog and get the 6300? My ham activities consist of DX chasing on SSB on 20 meters and shorter wavelengths and I'm just getting into digital modes now. I don't work any VHF or use FM. I live in a high QRM urban area where outdoor antennas are not permitted so I'm getting by with an attic fan dipole connected to an automatic tuner mounted in the attic. I'm presently using an FTdx3000 with good results but I'm interested in improving things more. Background QRM on a good day in my QTH can be S9. For these conditions which SDR radio would work best? Would the 6300 still be a best choice? Or would a good used 3000 or 5000 be good? 73s.