Going back to the basic x11perf microbenchmark, with the 500px PutImage Square test the Ironlake SNA back-end was faster but Sandy Bridge hardware had regressed noticeably.
The "Fill 300 x 300px AA Trapezoid" microbenchmark in x11perf was a striking win for SNA.
When compositing a 500px pixmap to the window, SNA was also much faster for all three hardware configurations.
Compositing from window to window was also much faster with the Sandy Bridge New Acceleration mode.