I had forgotten how big a change conversation view was compared to other webmail.
Also for what it's worth, I still use the Basic HTML view because I find it a better experience, so AJAX was definitely not the selling point for me. The 1GB thing was a huge factor though.
For me, the basic view has always felt neglected and kind of halfassed. The full experience has fully styled UI elements where as the basic view just defaults to the browser defaults. Outlook does this too.
To me it just feels like basic view is just v1.0 from 2004.