Noren, I've been way too busy to play with Roadkill, but am interested to try it out. The W map coordinate is used for a 3rd axis of mapping space (usually depth), which in Max at this point is only used by 3d procedural maps (Noise, Cellular, etc.). I wish I could use volume textures in Max, but there's no interface for…
Yeah, I get that sometimes when using the "Best Fit" button in conjunction with Planar Map, it just throws some of the verts way off into W space for no good reason. Kind of annoying (although worth noting that you can still select it in Face mode). I usually just end up re-mapping the face on X, Y or Z and that fixes it.
Thanks for the input guys, EricChadwick's suggestion did the trick. The problem for me involved some simple shaped geometry with a lot of subdivs in it. Which seems to make 3DSMax's relax UV tool useless. So if I remapped some of those chunks I'd lose a lot of time unwrapping them manually from planar. That reset W to 0…