Morkonan, just a idea.
Did you check the sort order of the uv values in the obj files with different projection modes on one side and with rearranging the uv in the planar mode on other side.

What do I mean.
I remember  one of the purposes  of  STOMP.  There was (is) a flaw in poser up to version 6. If in 7 I don't know at the moment.
If you have several material zones in a object, this may be saved as single divided parts as they are coming handy to the model app while saving.
If poser is reading such clustered materials it need's much much more time as if that material zones are saved together.
So STOMP as also the riptide object exporter for C4D (same author I guess) are saving that data sorted by material.
So this will change the sort order in obj file and that load's than quick as the wind.

May it be that such a ordering problem is touched here again.

• If you start with a planar map and later rearrange that map does this change the order while saving in object files.
• And is the sort order influenced depending which map mode you choose first ?
• If so what will happen if you arrange the sort order of a cylinder map like the order of the planar map. Ok, this have to be done by hand editing the obj file.
  But than it could be clearer why map projection mode is of influence.

Just as an idea. Poser isn't doing things a logical manner all the time, is it ?