GWT vs Flex

We have now some experience with GWT while implementing an enterprise price management system's UI. There are some nice features that GWT provides, but there are a lot of pain also while using some 3rd party widget library, like GWT-Ext. In my mind, the main problem is that while coding the solution using GWT, you loose the feeling of the application (especially if using a wrapper around a native JavaScript library). But this is just my feeing and doesn't really show if GWT is bad or good. Related to the real problems, when we had too many records to render in a data grid, we faced some performance problems - rendering all the records took quite a time and stalled the browser instance until the end of rendering process.
The 3rd issue I find relevant is the amount of code had to be produced for the layout and interactive behavior of the application. The Swing-style coding is a real blocker. IMHO, GWT probably make heavier use of annotations, perhaps even introduce some custom annotations for simplifying the implementation of user actions (i.e. listeners as inner classes).

After we almost finished the prototype, I started to think that probably, GWT is not really what we'd like to use in our application for the UI. I'm still strongly convinced that for this application we need a rich UI to satisfy the user. Adobe Flex was the next technology in our list. More than that, Flex is approved for our internal development by the architects council. So one our colleague presented us how is he using Flex to implement a RIA for loan management.. and smashing!!! I really liked the code separation for the UI: layout is defined in MXML files, events for the UI components are defined in a separate ActionScript files, and some utility code can also be separated into other scripts. Further more, the speed of making a convenient application was really fast. And also the amount of code to be written is much less than with GWT. No layout problems in the resulted swf, rendering a data grid with thousands of rows was just blizzard-fast compared to JavaScript analog.
I found some comparisons of GWT, Flex and Echo2 on the web: one and two

Both GWT and Flex 2 are Rich Internet Application (RIA) frameworks whose code is downloaded and executed on the client side, in the browser. GWT compiles Java code to JavaScript whereas Flex compiles a combination of ActionScript and MXML code to a Flash swf file.

And here's the quote I was waiting for:

...both GWT and Flex 2 have different situation where they each are better suited. HTML, CSS, JavaScript are still the best option when developing a web application intended for the general public. Flex 2 is would fit well when developing flashy business minded applications with a targeted audience.

I think this describes our case the most - a targeted audience.