I can see why a serious contester would want the RX366 but as a DXer who just fools around in contests and doesn't do SO2R, I personally don't feel the need for it. I would rather not give up general coverage, which I use for WWV, KPH/KSM, Armed Forces Day, etc. I do run the v3 firmware for my 566, and find the SAF feature very helpful. 73 Ray W2RS