Have had a chance to use the radio with the AF5400s. While I am pleased generally how things work I have noticed a few 'bugs'.

When you access the virtual keypad and then enter a radio frequency, pressing ENT to cause it to go into the standby frequency slot, the BACK button doesn't work at this point. You have to either swipe the keypad to the right or press the COM button to remove the keypad from the screen.

The box in the centre of the virtual keypad allows you to enter an airfield ICAO designation (to do a frequency look-up) when you push EDIT via the right hand knob. Despite entering a new identifier via the knob it is not clear how you actually enter / activate it. When you change the designation from say EGLL to EGLD, ACTV appears under the right hand button (next to the knob). However, selecting this causes the system to ask "Switch to Internal Navigation?"...this isn't really what you want to do from this screen...you really want to view / select / activate / the frequencies associated with the selected aerodrome identifier.

Moreover, if you enter a new identifier, for example you enter EGLD (when previously it was set to EGLL) and then go to the FREQ tab it will still show the radio frequencies for the previous airfield (ie., EGLL) although it shows the selected airfield (EGLD) in the box at the top.