i believe those instances are because there it is being used in a business, i.e to gain or generate income.
if a musician purchases a score and does a free program and gives all the right credits to the composer, arranger, etc. i think that kind of 'non commercial' use is essentialy 'personal' which is okay unless the work explicity states that persmission must be obtained before any public performance or presentation
yes, but what if your free program gets you noticed by some record-company guy who wants to sign you to a big-time deal? now you've been hosed by the intellectual property goblins! and seriously, what's the point of buying a score if you can't even play it without asking someone permission? it just seems ridiculous to me. sure, the composer should get well compensated for writing good music, but shouldn't that be built into the commission for writing the work, and the royalties for sale of the score, and the royalties for sales of any recordings? how many different times should the composer take a cut? (please note--I'm being argumentative, purely for the sake of fleshing out the discussion. most composers are starving, even the good ones, and should really get more money for what they do. but I still disagree with the system for how they get paid)
anyway, back to the question of the thread. surely there's at least one bach toccata worthy of mention?
and while I can't really comment on the relative difficulties of any of the listed toccatas (they're all way beyond the level where it matters to me at least), I must say that in general when it comes to listening to them I would go ravel/debussy tie, then prok, schumann last. but that's just me, your results may vary.