No I'm not using DWG Viewer.
But I was wrong. Unchecking the mirrored check box and setting the text origin to center is solving the problem.
But the DFX export is not noticeing the test property changes while the export window is still open. That is why I was not seeing any differences in the output.
Anyway it is strange behavior to not get what I see when using dxf export.
I do not think it is a problem of the dxf viewer. I'm using SpaceClaim to test the output. But I will look to check a second tool.
And I will have a look on the IDF.