On the 440 when you rotate the frequency knob, the list of suggested frequencies opens (which has the needed frequency about 70% of the time). Rotating the big multi-function knob moves between pages of frequencies ("Airport", "Enroute", and "Recent"). Rotating the small multi-function knob scrolls through the list of presented options. However, on the 540 both the big and small multi-function knobs do the same thing, i.e. scroll down the list of presented options. To change tabs from Airport to Enroute to Recent, the "Freq" button must be repeatedly pressed. What is the logic of having both knobs do the same thing? I like the 440 multi-function knob logic better.

Regarding the auto-population of suggested frequencies when the left knob is rotated, I understand that the 540 has a handy-dandy "Freq" button. But, it might be nice to have an option in the Setup for the list to auto-populate.