Feedback for Vaadin wanted

Has anyone used vaadin in a rea开发者_JS百科l project and wishes to share his experience? I am amidst a framework selection process for a RIA project and any feedback would really help. My key concerns are productivity and performance.

It would really nice to know how you would compare it to the more mainstream JSF+Seam stack, if you have worked with it.

Cheers!

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There is a list of organizations and project using Vaadin at vaadin.com/who-is-using-vaadin.

The performance / scalability has been nicely summarized in this video blog post: vaadin.com/blog/-/blogs/server-side-ria-scalability

Comparison to other frameworks is also available at vaadin.com/comparison