How is computer programming non-scientific? You think it's programmed so it gives out a saw if it likes you? No. There's obviously some math to it. And it can be proved, it just won't unless CraigStern decides to prove it for us. He said so himself, that's good enough for me.
Aside from the Bronze Golem battle, which doesn't pay much, with the somewhat debatable Spin Saw chances, the Mechanics are the ONLY repeatable battle until you get 30 Psy Power, aren't they?
Also, with the Spin Saw, you have to return to Somnus every time to sell them, since you can't have more than one. With the Mechanic Battling you can just grind away.