I am currently operating a ProIII and am very happy with its overall performance despite being somewhat dated. I'm considering a 7600 and have been researching its performance for some time. I've read Sherwoods stuff on the narrow roofing filters and it makes sense. Stating the up conversion 64.455 mhz 1st IF is why the 3 and 6 khz filters are not what they claim to be. Has anyone actually done any on the air testing with these two filters in a crowded contest? What was your impression?