It's simple:
- If there is no content on your plain html page there's no content
for GoogleBot (or any SearchBot of the big search engines to date)
- If you use Google's Ajax crawling approach you can turn a "blank"
ajax-only page into something the GoogleBot can index. Btw - Bing is
also supporting that spec. Downside: You need your own HtmlUnit that
turns ajax-js into html.
We are currently experimenting with this, but I am not yet sure if it
makes sense to use the Ajax Crawling approach for a site that heavily
needs good SEO.
A big blocker is also: If (and nobody knows really if they do ) - if
Google takes into account the speed when crawling sites via
_escaped_fragment_ it will almost certainly destroy any SEO ranking -
because crawling an Ajax site by your own HtmlUnit and returning the
result will be slow by definition.
Not exactly a GWT problem. But a problem.
Hope that helps,
Best,
Raphael