An updated version of the Revision Demo has been released. Version 1.2 brings a totally new Hong Kong chapter and last NYC mission. This release also fixes some bugs that were found from 1.1. Anyway, backing up your Deus Ex maps is not necessary
From the readme: My most ambitious project in Deus Ex. This mod will provide a whole new concept of Deus Ex weaponry. Forget the big guns, the bullets, the rockets...this mod brings you MAGIC!
Deus Ex: Revision is a large-scale re-imagining of the world of Deus Ex, bringing a tightly integrated aesthetic-oriented approach to the original gameplay.