RCP versus AJAX

So in evaluating possible tools sets and app frameworks for a new product aimed at the consumer and small business market, what are the considerations in making this decision. There are some bleeding edge trends out there that have a lot of advantages over traditional Microsoft app development. The two that I’m currently considering are RCP from the Eclipse group and a Web app using AJAX.
There are several advantages to both strategies.
A lot of it is going to depend on the reality of being able to create a fully functional UI using AJAX. If it is possible to do everything in the browser that used to require a downloadable application then I feel that the AJAX route has a lot of advatages.
1) No need to distribute the application.
2) Don’t need to suppport client install and versioning issues.
3) Backward compatibility with existing client base problems disappear.
4) Hopefully easier cross platform support. (Depends on Browser issues).
5) Client is able to access application and data from anywhere with internet connectivity.
With initial testing some issues are already showing up.
1) Tools support for complicated javascript development is very limited.
2) Pre-canned AJAX type tools are getting mixed reviews.
3) Debugging javascript problems can quickly turn into a nightmare.
So, it’s still too early to determine how this experiment will turn out. The hurdles of using AJAX effectively look like they’re doable.