[necroflux]

Indeed the vast majority of X-cart users are using Authorize as a background payment process, and are still using 4.1 or 4.2. Let me second the fact that not programming this payment module to be compatible with these still heavily used versions would be a devastating oversight that would alienate a huge number of your customers once the PA-DSS compliance deadline passes.

I would go as far to say that it is your responsibility as a company to ensure that to a certain degree all widely used versions of your software receive a working payment module that is PA-DSS compliant.