Quote- My vector disp setup that worked flawlessly is to use an image map going into the function of a vector displacement shader, thats it.
I didn't need to flip colors, rebuild vectors, rotate vectors etc.
Yes, thats right. You can use a vector disp and a vector displacement shader alone easily. so long as the vector map is EXR. This is the best/fastest/easiest way in my opinion because there should be no need to manipulate the terrain with other functions, since the terrain would already be just the way you made it (wanted it to look like) in Z or mud. The big thread (16 pages I think it was) is not the only thread on this topic. Some of the info is scattered in the forum. But to summarize that, yes, just use 2 nodes. This is a good way. Though you seem to know it now already based on the quote.
I think the only problem here is that we don't understand the exact problem you are having is all. But if it is only testing Z the way J did. I can't help with that. I use Mudbox and it does not work the exact same way. But I have been through this workflow a lot. It works pretty well. Though there are a few limits, but those are in Z and Mud, not TG so much.
Quoteit would be great to see a tgd setup of what has been described.
Since you use Z-brush, your in luck. "chris_x422" posted files from his own work. He included the Z-brush maps, I believe. Not sure about the TGD. But he posted finished images. So with the files and the images he posted, you should be able to reconstruct what he did. Than look at the images he posted if they are the same, than you are doing it the way he does. He is a pro by the way ( I think that should matter) he worked on some big films. I mean, his workflow is proven.
chris_x422 also posted a tut based on his work on the film "Snow White and the Huntsman". In which is shows how he used TG and Z to make a scene for the film. Its here some place, I am sure one of us can find it for you if you like.
My point is this does work. ITs just hard to sort through and there are some tech limits.
http://www.planetside.co.uk/forums/index.php/topic,16110.120.html scroll down a bit.
This is the first post by chris in the big thread. Read forward from there and you will run into his files. Use those to test your own thinking.