The templating system can in theory support multiple engines (it has been designed to allow plugable implementations) but currently we only have one implementation
Once we begin to expose these services more we will start to add other templating support such as XSLT I would imagine.
We intend to move the templating support down into the repository as a service - currently it is part of the client code only.
I actually made simple implementation for XSLT templating (I can add some comment there and contribute the code). Then I add <engine name="xslt">correct.java.class.name</engine> inside the templates element in web-client-config.xml. Then I couldn't find any way to select which template engine is used for each template.
Only way to use it so far is comment out freemarker engine element and change name xslt to freemarker…
Your question is fine I understand - at the moment we simply have not exposed a way to change the template engine in the web-client. So for now your solution is the only way to change the engine.
Latest Template Guide documentation for Alfresco 1.1 now available, including information on XML Node processing in templates, dashboard views and using/configuring the new Template Service in the repository.