Just this past weekend I saw Susan Chang, Senior Editor at Tor, speak. It really sounded like Tor was a great place to work and a great place for authors. The DRM-free change supports that idea.
Julie Crisp of Tor wrote an article about how things are going after a year of DRM free sales.
"...we’ve seen no discernible increase in piracy on any of our titles, despite them being DRM-free for nearly a year."