Re-lip material and sharp lip syndrome. I don't think a lip material has any impact on how sharp or smooth the transition is. It's those pesky pasted on lip textures with no blending that are the real culprit of the dreaded sharp lip syndrome phenomenon. However If Odf went with a completely seperated lips layout from before it may have been impossible to blend any texture.
I still think it will be difficult with the current chin/lip split mapping but not impossible.

Odf as you know I still prefer the chin/lip stitched but I think it's cool your trying something different than what may be considered standard by most.  Im certainly not opposed to experimentation and discovering new ideas otherwise innovation would not be possible but then again there's the old saying "If it ain't broke don't fix it". I just think the weaknesses ( possibly harder to texture seams in 2d painting apps, harder to apply complex shaders options with mask maps ). will out-weight the strengths ( less distortion ). Im not saying either way is better just what I think most may prefer. I think the V3 re-map is a great idea but I agree with you that you should do your own and leave V3 re-map to others.

I think you should try stitching the chin/lip and make a test map with a basic color fill with some noise to simulate a detailed skin and see if the stretching would be acceptable ( if you haven't already ). Also I have seen a technique ( never tried it ) on head models where you actually flatten/smooth out protrusions ( nose,lips etc.) on the mesh itself then start uvmapping from there. From what I could see it avoids distortion really well but it didn't look very easy to do or time friendly.

A few post back you mentioned moving verts. Blender's Uv mapping has this capability. You can even pin certain verts in place to get a better unwrap and it helps with symmetry and overlapping woes. Here are a few of the keys I use when adjusting UV's in the uv editing window.

Ctrl+Z=Undo
RightMouseButton=Select individial verts
Hold Shift+RightMouseButton to select more than one vert.
A=Deselect
B=Box select for selecting multiple verts.
B then B again=Brush select. You can scale the size of the brush with the mouse wheel. Right click to confirm. This one makes uv editing kind of fun...kind of ;)
P=Pin verts
G=Grab verts
S=Scale verts
using the X,Y or Z key right after G-grab or S-scale you can move them along a fixed axis for more precise control.

Select a vert and then go to Select>linked Uv's makes selecting seperate pieces ( Islands) easier.
UVs>Weld/Align>Align X or Y makes it easy to get a perfectly straight centerline to pin so that the object unwraps symmetrical.
Image>New>Click and type in the size then click UV Test grid to check  for distortion.
There are lots of other things but these are the ones I use the most. Ok now I'll quit harping on Blender so much lol. I actually think the best approach is to use multiple tools and take the best of the best ( or atleast the more hassle free tool ).
Hope it helps :)

Cheers
JB