Why export empty meshes? Why not use Empty objects?
Sorry when i used wrong words, anyway i use "empty objects".
(i consider a mesh or an object the same, especially when they are empty.)
I use empty's as offsets in Array's.
You can give a rotation to an empty in any direction even combined.
This is very usefull in array's for modelling "rotated stairs" or "leaves around a tree" etc.
Transforming the empty, results in transforming the array.
it add's the difference of -distance and rotation- of the object centers between the
first array element and the reference empty, to the next array element.
Simply "grab" the empty and move it .
you see the result in real time.
I have been looking quite a while for what i did wrong when my export failed.
Agreed, its not very important , assigning a material is done in a split second.
It's just "Odd" you have to do that.
