I noticed from the screenshots you guys might have run into the same problems as I had. There's some troublesome light-distribution issues on some of these, notably the NORMALS on the vertexes of the omni quads at the top of the arch slopes. It only seems to be present on arches with even-numbered dimensions (the 4x and 8x, not sure about the larger 6x)
The problem is the original non-flipped arches don't even out those vertexes to NORMALS of 0, rather they stop at something like -0.19. When you flip them, the new arches get the opposite, 0.19, which creates an overlapping "gap" in lighting information and results in the ugly mismatch in lighting that you see here.
The perpetrating omni quads are the 5th and the 8th ones if you guys want to look into it. It would be great if Badspot could tweak the original arches for the next version, so we could get some nice lighting that matches.
