I managed to get this work in ZBrush after all - but it's still not a perfect match due to the UVs not being exactly 0.0 and 1.0. I assume my earlier noise problems raised from the UVs being "over border"? Like -0.0001 and 1.00001 - is there a way to snap them in the borders in Max?
I think i know why you get issues on some gifs posted and it's because of your Mirror settings. You have Border attribute set to "Merge Border" but then Merge Threshold set enormously high (153) while it's should be something like 0.01. http://i.imgur.com/fu1Cvpr.gif