Interesting concept. You could probably improve cutting efficiency if you were to match the lengths of the pivot links better making the whole system closer to a parallelogram. As is there is a noticeable upswing in the cutting action so you're only utilizing a very small portion of the blade at any given time. Making the saw move in a more linear fashion would keep more of the blade in contact with the work yielding more cut per stroke (though that could result in excess torque requirements).