I absolutely cannot stand medium nibs, it's horrible for smaller or narrow handwritings. Also, with a decent quality paper F nibs are just as comfortable to write with.
Medium can mean a lot of things. My Parker Vector's medium nib with Parker's own ink is equal to broad on many other manufacturers. Kaweco's medium is almost equal to Lamy's fine.
All nibs become quite comfortable after they are shaped by your hand and writing :)