I enjoy this one taking coins, but maybe I'll also wire a hidden button like you say. On my first MAME cab, I put a little button in the bottom of the player 2 coin return.
I'm already kind of tired of this Soul Edge... I'm not big on fighters to begin with, but if I'm going to play one I prefer Tekken. I just told one of my buddies though, and he went nuts. He was in the Marines and there was a Soul Edge machine on base.