As a
TRUE ASP.NET AJAX Control you have almost unlimited possibilities with
RadGrid for ASP.NET AJAX client-side API.
I've spent ~ 30 minutes to create
small and powerful demo with client-side data-binding to 1 mil. records using
WebService and LINQ. No traditional post back/ajax requests to the same page, no ViewState - just
pure JSON.
To see the traffic between client and server you can use FireBug, HttpWatch, Fiddler or any other similar tool. Here is a small screenshot from FireBug:
Enjoy!
[Source code]