Honestly, I've always felt that Fn keys were an outdated and faulty design. They're too far away to reach gracefully, usually offset from the standard zig-zag of other keys, and awkwardly multi-roled with screen/sound options on most keyboards.

If I'm in an IDE that uses a function key for something like 'compile', I usually rebind it for my own sanity. I have mixed feelings about this update (contextual buttons are often terrible, and I don't mind escape), but losing Fn won't really matter.