Some more delta experiments! It's better in motion, but I couldn't be bothered to make an animation. Antonia's back at subd level 1 with a morph that has the delta [0.0, 0.01, 0.0] at every vertex. The left image shows the morph dialed at 0.0, right one at 0.1.

The tile pattern is wider than high. If you look closely, you can see the vertices move along the positive u direction. The interesting stuff happens at the texture seams and also at irregularities in the uv maps. At the seams, we see that one side wins, but it's not obvious how that side is picked. At the vertical seam down the back, it's consistently the right side. At the horizontal seam, it's sometimes the top and sometimes the bottom.

Spots with UV irregularities are also interesting. It seems to texture quads are split into pairs of triangles and then the uv coordinates interpolated for each triangle individually. As there are two ways to split each quad, there's another opportunity to "disagree" with Poser and mess things up.

-- I'm not mad at you, just Westphalian.