I'm a long time Java developer who has been building UI with Adobe Flex for the past few years. I'm looking to broaden my repertoire with a RIA technology that runs in a plain-old browser, no plug-ins required. I've read a lot about GWT but don't know much about JSF, especially given the varying implementations. Below are some criteria that are important to me as a developer. I'm hoping that the community might be able to tell me about the strengths and weaknesses of GWT and JSF in each:

• Layout: is it declarative, programmatic or a mix of both?
• Control library: how rich is the available control library? How easy is it to extend or write custom controls that "play nice" with the built-ins?
• Javascript: how much of it do I need to write in order to be successful with the framework?
• Cross-browser: assuming I'm not writing a lot of my own HTML and JS, do the frameworks function equally well in all modern browsers?
• Tooling: is a rapid edit/refresh cycle available? How easy is it to debug the client and server code?
• Bookmarking / Browser Navigation: this is a common problem in Flex; does the framework play nicely with these?

I would love to hear any other important pros / cons I might not have covered. Thanks!