OpenRasta vs. ServiceStack vs. Nancy

I am comparing the above structures and notice in ServiceStack that it can output different formats, not just JSON or XML, but CSV, SOAP, text and HTML. However, when I compare this to OpenRasta and Nancy, I don't find this mentioned explication in their documentation.

Hence, does anyone have any experience with these frameworks, and if so, can they output more than just JSON and XML?

Also, is it possible to use any of these frameworks as a web service on their own and then use, for example, a WinForm application?

Greetings