I've had this drive for a few weeks now and my benchmarks have always shown the burst rate lower than 100MB/sec. This is my first SATA drive and from what I've read looking at the burst mode is the only way to know if you are in SATA/150 or SATA/300 mode. So I put the dip switch for SATA/150 mode back on and the burst rate doesn't change which leads me to believe the problem with the drive is it is ALWAYS IN SATA/150 mode regardless of setting. I've taken to leaving it in SATA/150 mode so I don't loose the dip.
The new 1.5TB seagate seems to have this burst rate problem too.
SATA/150 Top, SATA/300 Bottom