Back in May I carried out some performance tests on Intel's Sandy Bridge comparing UXA, SNA, and GLAMOR for 2D acceleration. In this article is a similar set of tests but for Intel's latest-generation Ivy Bridge HD 4000 graphics.
In the May article I covered Glamor acceleration in more detail for those interested in the background information. Since then, Glamor has not advanced too much while SNA acceleration continues to be worked on by Chris Wilson in the mainline xf86-video-intel DDX driver.
At this point it looks like SNA will ultimately succeed UXA. Ubuntu 12.10 is also likely to default to SNA as one of the first distributions migrating to this faster "Sandy Bridge New Acceleration" architecture.
The Intel Linux graphics components were running from their mainline Git code-bases as of the time testing commenced in May on the Intel Core i7 3770K hardware.