Hi,  I just read about your endeavor of transcribing piano rolls to
sheet music on MMD.  "Notation Musician" has just what you are looking
for and it really works well, but first the roll must be scanned into
MIDI format.  I have been using it for at least four years.  If anyone
is interested there is a free trial offered at  http://notation.com/ 

As you probably know many MIDI pieces are single staff notation --
Notation Musician will also split the left hand from the right hand.

Best,
Tim L'Amoureux