Yes, mixing and maxing is very much expected. SWF is not all or nothing. It is designed to be used WITH traditional controllers, e.g Spring MVC controllers, Struts actions, or JSF navigation handlers -- as a compliment. After all, SWF itself is a specialized controller that is considerably more powerful, fit for controlled navigations that drive business proces workflows.
See the flow launcher sample for the various strategies for launching flows within an application.
Core Spring Development Team