We use extjs and openacs extensively, but we don't use ad_form. Ultimately, trying to have code generate javascript is going to be much more of an uphill battle than just writing the code directly. The only exceptions might be highly-supported toolkits like Google's GWT (and especially with something like the sencha GWT tools on top).
Writing javascript doesn't have to mean you end up writing the same code all over though - it can be written MVC style, made into reusable components, etc.
Taras
