Battery bay ribs are intact like said before for strengthening reasons. I only removed the one in the 2cell bay to give a flat floor to the esc.
But personally I would like to see a factory chassis without cell holes (or even filled thin enough to cut with an x-acto if you wish to use nimh). This way we give preference to lipos, the future right now.
Lowering the lipo is other story..
Is the X60 chassis made without cell holes?