I don't use them, the 96% K4v2 and v3 are what I prefer for the compact but nearly full sized.
The k17 pro is ok but I don't enjoy the extra size. The smallest keyboards I can use are 60% or 10 keyless since I use function keys and num pads all to often.
If I was a writer and not do doing math/engineering related things I would skip the extra keys.