If your clients only use your provided libraries then there is no difference between SOAP and REST in this instance as the primary attraction of REST (accessing

If your clients only use your provided libraries then there is no difference between SOAP and REST in this instance as the primary attraction of REST (accessing the methods through HTTP requests) will be abstracted by the library. So either that 25% wants a RESTful interface because they're going to opt not to use your libraries or because they're conditioned to vote for REST over SOAP.