From my tests with UDIM VRayDispMod, both SubDiv and 3D options break at the vertices of UV seam lines…I hadn’t tried 2D. My work around until a fix is implemented is to use a Max SubDivMod (Turbosmooth or OpenSubDiv) and DispMod with a Composite map. Seems to be more of a render/resource hog, but it doesn’t render with a “zipper” artifact at the seams.
I look forward to what Chaos comes up with.
Thanks