Juozos, I'm not sure whether I already responded to this question, here,
but for what it's worth....

One would think, In the case of BACH's keyboard works, especially the
fugues, that the capacity to separate voices via MIDI would be an
advantage.

My own experience, however, is that this is not the case.

Keyboard compositions seem to be made for human hands.  MIDI transcriptions
without reference to that fact--without, that is, very subtle adjustments
for phrasing, the precise length of each note, the weight (or "velocity")
given to each note, etc., etc--tend to sound very odd.

"Technique" is a prime example.  Many, if not most, "MIDI" artists believe
that MIDI is an advantage, because it can play every note perfectly evenly,
thus making technique "perfect," as it were.

This is a huge misconception, and the result is mechanical, wooden sounding
MIDI transcriptions.

Technique in keyboard playing is NOT the development in one's hands of a
perfect "mechanism" for playing, it is the art of playing scales, and the
like, with BEAUTY.  That is something quite different.

Alfred Brendel's Mozart, for example, seems to me "technically" gifted,
his scales utterly smooth and legato, but this is not because his timing
and touch are mechanically perfect; rather, it is because they are--for
want of a better word, "aesthetically" pleasing.

So much of MIDI that is REALLY GOOD does not take advantage of MIDI's
capacity for "perfect' technique.  Rather, the MIDI performer plays the
material in himself or herself, and uses MIDI afterwards only as a means of
editing the material--which is something MIDI can do with great precision.

MIDI is really a hurdle to be overcome in making music, not an advantage to
be siezed.

John Grant
http://www.mp3.com/stations/bach_wtc_1_part1
http://www.mp3.com/stations/wtc2