I touch type, and I've never touch typed a function key.
I realise that whilst just about everything else I do on the keyboard is proper touch (based from F-J), I have to move my whole hands to use the FN keys. I will nevertheless hit F5, F9 etc for compiling / break points / step debugging without looking down at the keyboard.
I'm listening to music all day. Changing the volume and skipping tracks without looking is great to keep the flow going.
I never realized all of the complexity that developers were required to deal with.