We have the Authorize.net CIM module available for a while now if you are still interested in it. Many banks accept this as a way to take X-cart out of the scope of the harder PCI questionnaires. We haven't run into one yet that didn't accept this or our Authorize.net DPM solution as something viable for ease of PCI compliance.
http://www.bcsengineering.com/store/authorize.net-cim-module.html?MMCF_xfCIM
Carrie