Max, better most modeling tools, allow to assign more than one uv-coord to a single vertex. In this case, you need to split your vertex and assign the different uv to unique vertices. That is the reason, you see no artifacts beside the expected seams when using max (the border vertices got more then one uv-coord), but got warping artifacts when using shared vertices in your mapping code.
No but when I use the UV's that were exported WITH Max, I get the same result as in Max (the desired result) on excactly the same mesh. So it is litteraly JUST the UV coordinates ons those edges that differ.