Re: Hardest instruments to play
pedal steel is pretty easy to play. the strings are usually tuned to an open chord and you basically just play bar chords. there is also a visual reference of were the notes are. you just use the pedals and the knees to change the tuning to fit a chord into the key or to play different chords (major, minor, diminished)
bagpipes are physically demanding to play but they only play one scale + one extra note.
what about a full pipe organ? you have to have 4 way independence plus control a bunch of pull stops and unlike drums you are actually playing different notes with your feet. obviously terry bozzio is doing alot of stuff with his feet but i doubt he has 32 notes like a pipe organ. the only thing easy about an organ is that they use the standard keyboard which is pretty easy to play.