I'd really like to fix the way the ASE exporter (and others) orientates the middle edges of the quads it exports. They are opposite of how they should be, as seen in Radiant. To illustrate, I have this pic below - on the left is the original patches that I exported, and on the right is the ASE model that I imported back into Radiant. You'll see how the inner edges are orientated differently, and in this case gives a different shape, and in other cases may affect the way the textures are warped on these faces.
(I added the extras lines in the orthographic view to demonstrate this, but they are 4 patches, not brushes)
I'm also trying to figure out how to do this in Blender, but I don't think it's possible. Perhaps Meshlab can do it. There is a line in the Python script here:-
for x in reversed(winding): verts.append([x.vertex.x(), x.vertex.y(), x.vertex.z(), x.texcoord.x(), x.texcoord.y() * -1, x.normal.x(), x.normal.y(), x.normal.z()])
A tweak to this may be what's needed, but I have no idea how. I might try to play with it in a while.
Exporting as OBJ corrects the orientation of the inner edges of the quads, but using this method loses the material headers, this information is not exported.