Hmm, interesting. I've used the m2/5 formats before when working with modeling for other engines (I found them to be one of the most compatible, with the majority of 3D engines supporting them).
Incidentally, I don't suppose one of you 3DSMax users could fix the export script so that it works with the newest version of 3DSMax? Most of us use blender, thus why we cannot keep it updated, but depending on the changes between the two versions, it may not be a huge change to adapt the export script to the 2009 version of 3DSMax