I've been investigating the use of your common payment gateways to incorporate into one of my components.
But I am encountering a problem with your plugins - most of them assume that DS has already been defined as DIRECTORY_SEPARATOR. This is no longer part of Joomla 3.x core code and needs to be updated or defined as needed in each of the plugins.
Are the gateway plugins still being actively developed? Is there a Joomla 3.x compatible set of code available?