In a similar place to OP having various DC motherboards and want to know which is the 'best' candidate for a DCHDMI install.
With DCHDMI being quite a commit to make, I am also looking for some definitive clarification (and I did try emailing citrus3000psi to sadly no avail). I'm also natively PAL region, and run games from GDEMU. Ideally I want to be able to run games from all regions on the DCHDMI machine, and I wonder if a vanilla board (using the GDEMU menu for multi-region support) is going to be more compatible than a region-free BIOS modded machine, and then which region board is the best start point for either solution?
The last lot of googling I did seemed to suggest that an NTSC machine with region-free mod and R422 mod gave best compatibility, but this was before DCHDMI was a thing, and I have no real understanding of how that affects the video output. It isn't really entirely clear to me quite what standard DCHDMI outputs at; Wombat's post above seems to suggest it uses VGA source in some sense, but it can also play the games without VGA support too.
If anybody can explain it all to me, it would be much appreciated!