Simpli Software's HD Tach is described on the company's web site as such: "HD Tach is a low level hardware benchmark for random access read/write storage devices such as hard drives, removable drives, flash devices, and RAID arrays. HD Tach uses custom device drivers and other low level Windows interfaces to bypass as many layers of software as possible and get as close to the physical performance of the device being tested."
HD Tach tells much of the same story. The Micron C300 is the fastest drive of the bunch when paired to a SATA II connection and its lead simply gets wider when connected to SATA III. In fact, burst, read, and write speeds all improve significantly when the C300 is connected to SATA III.