I have noticed another issue with eSATA on Ubuntu/9.04 in addition to the automounting one. When the HDD is plugged in through eSATA before the OS boots, a 3Gbps SATA link is established. However if it is plugged in after the OS boots, a 1.5Gbps link is established. While this is definitely better than USB, it is still suboptimal. Hoping to find a solution for this problem sometime.