Since the glue that I used to stick the flat loop onto to the back panel finally dried, I have been testing the GE C409's performance compared to the Electrohome, my favourite modern digital PLL radio, and my first one, an old Sanyo SW-MW tape recorder. I have considered all to have good AM broadcast band performance, which is important to me.
After filter capacitor replacement, the receive audio is very clean and quiet. It does not generate much internal noise, which is kind of surprising given that it is directly line powered.
I guess that eliminates a power transformer giving off stray line frequency that would be picked up by the radio portion. So that gives it a nice low noise floor and it is nicer to listen to weak distant signals. I generally use 1570 CKMW as a good test because the frequency is generally pretty clear and available most evenings, so I can hear how well the radio picks out the weak field strength. I wonder if the fact that it had 6 tubes instead of the usual 5 improved sensitivity.
Of course the inherent disadvantage to mechanical tuning variable capacitors is that they are not as precise compared to modern digital tuning, but the C409 has the classic air-dielectric solid vane variable capacitor that doesn't get scratchy like with the more compact film-dielectric types. I was also surprised that I did not have to clean the volume potentiometer on the GE, usually that is the first component I have to take care of with old radios.
The knobs are very nicely laid out, good for 2-handed operation when scanning the band. And it has a conveniently placed external antenna connection, indirectly coupled to the internal loop, which the other 2 do not have (although portable vs. tabletop design differences).