Olaf,
What I wasn't considering is that in UVLayout, when you UV map something in Sub-D mode it's because you intend on using it in sub-d mode. So it builds the distortion into the polygon mesh, which, as I already pointed out, straightens out when put into sub-d in a program that can do it...
So, UVL was compensating for it, and it is clever. It's just not meant to be used on a polygonal mesh. ;-)

I don't know if there's a way to un-distort it in UVL though.
Soon as I get a chance I'm going to redo it in regular polygon mode and see how that turns out.