I tried seaching for head to head benchmark results comparing access times of LSI controllers to the common Intel SATA3 controller. Didn't see anything. I did run a simple AS SSD benchmark on both and the access times were nearly identical with the same brand/model of drives, Vertex 4s.
The drives are different in NAND. Intel for the 256 and Micron for the 512s.
Let me know what access time benchmark to run and I'll run it.