Yup. That's why I said I'm reconsidering now. I have EE background and unless someone has schematics for the trigger or a definitive statement from Mamiya, it is better be safe than sorry. Especially with such an expensive piece of equipment. On the other hand, here's what the manual said:
Originally Posted by Noble
"When an electronic flash is connected to the hot-shoe, current moves through the X contact. So be sure to put the safety cover supplied with the camera on the X contact so that you will not receive an electric shock."
It's kinda hard to get an electric shock with just 6V on the contacts is it? So unless I'm misreading it, they must be assuming a higher voltage there.