It is leaf switch, not leaf spring.
They are great all around sticks, but the lack of distinct positions might not be the best for fighting games.
My reccomendation for the best fighting game stick would be one of what I call the "Wico microleaf", which is the same basic Wico leaf joystick, but with microswitches instead. It has almost the exact same feel, but also has the exact clicky action you might want for your special moves.
They aren't that common, but they aren't "rare" either. I have at least one in my parts box. A lot of Sega games came with them around the System 18 era.