According to the link below XmlHttpRequest is included in Safari starting with version 1.2:

 

http://developer.apple.com/internet/webcontent/xmlhttpreq.html 

Safari also supports DHTML and HTML 4.01, according to this FAQ:

http://developer.apple.com/internet/safari/faq.html

From the links above it seems Safari supports Ajax technologies. In fact Microsoft's Atlas framework is supposed to fully support Safari.

This makes me think that calling Safari a down level browser is not exactly true. Am I wrong?