USB 3.0 has been a long time coming, and it looks like widespread adoption will take longer still. That's a shame, because USB 2.0 is painfully slow considering the capabilities of today's mainstream storage devices. Even with our enclosure's run-of-the-mill hard drive, we saw more than a three-fold increase in transfer rates by jumping to SuperSpeed USB. That's huge.
Of course, we also saw a similar jump in performance when moving the hard drive over to its native Serial ATA interface. eSATA hasn't really caught on, I suspect because initial implementations required an auxiliary power cable. However, hybrid eSATA/USB ports are slowly populating motherboards and notebooks, and they may offer a better interim solution until USB 3.0 sees widespread adoption and more robust implementations. The market is hardly teeming with hybrid eSATA/USB storage devices, though.
I suppose I'd be more enthusiastic about SuperSpeed USB if this first implementation didn't feel a little half-baked. The NEC controller doesn't have the host interface bandwidth to properly take advantage of USB 3.0's full potential, and the burst transfer rates we observed suggest other bottlenecks may exist. The U3S6's Marvell SATA controller has a similarly inadequate PCIe interface and some troubling performance issues of its own, too.
But hey, Asus says the U3S6 will sell for only $30 when it hits North America, which should be soon. So it won't cost much to add USB 3.0 and 6Gbps SATA to an existing system, even if these first implementations of the new standards may not be as good as more mature solutions that surely lie over the horizon. At least with the U3S6, you won't have to buy a new motherboard in order to make the upgrade.