That's great, thanks for the info.
Just to be clear, if I cut the trace on my board, the signal coming off the board is now a standard CGA set? And the V-sync and H-sync pins from the board are now combined into the Composite-sync output? So on one of the boards I was looking at, the composite-sync output would be connected to the "S" connection? (the board I was looking at had R, G, B, GND and S pins on the CGA input).
My monitor is a 13" in a Stargate cocktail, fully original as far as I can tell, and still giving a great picture. When I was playing it a few nights ago, I was just thinking about how old it is, and that it's probably difficult or expensive to get parts for the monitor if it ever needed them, so just thinking ahead to what options might be available if I did have to put some other monitor in there.