Hi Kai,
I investigated the issue and maybe find the solution to this topic :
viewtopic.php?f=28&t=53625&start=10
I discovered that these attributes are not recognized as file path by Maya:
octaneImageTexture.File
octaneAlphaImageTexture.File
octaneFloatTexture.File
as a consequence the File Path Editor can't work with these nodes
and the "Archive Scene" function in File menu doesn't work for them either.
SOLUTION:
At creation time these attributes should be tagged with the -usedAsFilename tag.
(As you are refactoring the octaneMaya nodes creation process, I think this information may be useful just now )