Well, Richfaces has the ajaxSingle options, which I guess is what you are after. Reading on the IceFaces website, this seems to be what they mean when they talk about "Direct-to-DOM".
JSF 2.0 uses the partial rendering model, the same approach as Oracle ADF and Richfaces are. Really, that was introduced by these projects and ICEFaces adopt that for direct-to-dom rendering. Direct-to-dom model simplified application development but for memory consumption and performance costs. Take a look for article at http://java.dzone.com/articles/performance-report-server-side about that.
Therefore, to decide proper framework for your project you should realize what is more important for final application, development time or performance.
For JSF-2.0 based RichFaces version we gouing to support event-based update model similar to Swing models that could simplifie interface devlopment without performance impact.
Take a look for http://alexsmirnov.wordpress.com/2009/05/28/javafx-as-jsf-2-0-vdl for even more ideas how it could work.