Take your time and good luck.
#3 was the right one.
Now for the bad news,there are some issues I didn't notice and/or think of yesterday.
Look at the no disp and the vdisp again and you'll see the shadows are the same.
I think Richard (cyphyr) had that happening before with displaced planes iirc.
It becomes more obvious when rendered bigger or with protrusions and so on.
That's of course not really desirable for object rendering.But there's nothing you
can do about it as a user,except cheating or tricking the eyes or postwork maybe.
Another problem is the fact that low poly objects can have pretty bad shadows also,
talking about the shadows that are on the object itself here,when the poly resolution
is too
low.So one has to find the right
balance.In other rendering apps you would simply
add some subdivision levels,preferably on rendertime,to solve that,for use in TG you have
to try with different polycounts to see what works best for your purposes.
ZB users will have to deal with ZB not exporting normals (less mb,smaller obj files) and
TG2 not generating normals on imported objects (other apps do that btw).There are
workarounds so it shouldn't be much of a problem.
Didn't get to test everything thoroughly yesterday,so some more tests are required.
Will keep you posted.
Does TGs renderer use smooth uvs internally?