Sorry, I mean it has the PC cable, I got used to referring to it as X-synch because I've a couple old "accessory shoe"/"cold shoe" cameras where I use the connection for electronic flash. I've incorrectly used it as a name for the connection (like some people use the terms rs232 and rj45 incorrectly).

The Bronica manual says the PC cable should always be connected, but I assume this is true only when NOT using the Speedgrip G, which I have. The Speedgrip has an hot shoe that does fire the flash, but this whole camera is a slightly different animal to what I'm used to, so I'm being extra dense.
Link to PDF Bronica Manual, it's on page 26:
http://www.cameramanuals.org/bronica/bronica_gs-1.pdf

I can't find a link to the Speedgrip manual, but have one. All it does is tell you how to attach it (which hardly seems necessary). For the Bronica flash it says consult it's manual. For other flashes all it states is:
"When using electronic flash units, other than Speed Light G1, check operations first before using them in the manual mode if there are dedicated contacts besides the X-synch contact."

I am pretty sure I'm over-thinking this.

The only digital camera I have ever owned was one of those "single-use" cameras. I bought it specifically to solder an USB connector to the board and re-use it. Basically, I did it for fun and to see if I could, just as I re-used single-use film cameras.