1. Is there any difference in video footroom/setup/pedestal between NTSC-U/C / NTSC-J games or consoles? 2. For GSM, other homebrew and the few games with a sanctioned 1080i mode, in what color space is the output - BT.709, BT.601 or yet another?
I'm pretty sure NTSC-U/C and NTSC-J are the same. Games are probably sRGB and their cinematics are probably rec601 but without test patterns being output it would be hard to tell.
If true (that is, sRGB and NTSC mixed) that would make accurate color tough to achieve...though I suppose it's really a question of the "reference viewing conditions" when these games were readied for release. Also, taking a second look at the docs - does analog component RGB, whether Japanese or not, have setup at all? SMPTE 170M (found here) makes it sound otherwise:
