I've made some progress on this problem, and have discovered something very strange concerning the ROG RAIDR in the process.
First, I took the RAIDR and attempted to install it on another machine (in this case, my office PC, a Lenovo ThinkCentre m91p). There, it functioned without issue. Note that this system has a Sandy Bridge MB with an Intel Q67 chipset, an i5-2400, and 4 GB of DDR3 ram; the RAIDR was in the one x16 PCIE slot and a USB 3.0 controller was in the other x1 PCIE slot, leaving two PCI slots free. The speed was not great - see here:
...but it worked. I grabbed an old PS2 keyboard from work, came back home, plugged it in, and - a miracle, it worked! Here is the RAIDR running on my machine, in the second PCIE slot (faster than above):
The speed in the first slot is effectively identical (maybe even slightly worse), so that doesn't seem to be an issue:
This is about half the speed quoted on the box (they of course note that it depends on the system), but still far faster than any other storage device on my system. Would be nice to know why it isn't faster still, but perhaps it's also a question of the block size being used by HD Tune when it runs the test.
In any event, once in Windows, I noted two devices listed in the Device Manager as having problems - the Marvell ATA Controller (Code 28 - no driver - the drivers that ASUS makes available for the RAIDR took care of this) and an OpenHCD USB host controller, which was complaining that it couldn't start (Code 10). Further investigations using USBDeview, found here:http://www.nirsoft.net/utils/usb_devices_view.html
...made plain a very, very puzzling issue:
The RAIDR, when it boots, is interfering with my MB's on-board USB hardware. However, it is not as simple as that. All of my USB devices work fine and show up in USBDeview, except
anything classed as a Human Interface Device (HID). The USB 2.0 devices on my system classified as HIDs include my keyboard, my Rockfire USB-to-game port adapter, and, bizarrely, my UPS (my mouse is plugged in to the PS2 port and so never had a problem). If the aforementioned devices are plugged in to any of my MB's USB 2.0 ports when the RAIDR is installed, they are not detected and do not function. Based on the behavior of my USB keyboard as described in my initial post, it appears that this conflict is independent of WIndows and occurs within seconds of boot-up. If I plug the same devices into the ports associated with my USB 3.0 add-on board, on the other hand, they work just fine.
With that in mind, I have purchased a PCI USB 2.0 card with 4 external ports and an internal USB header for the ports on the front of my case. I've also got a new, PS2 compatible keyboard coming. I have in the meantime disabled my MB's USB hardware, and the hardware issue noted in the Device Manager has disappeared as a result.
So, bottom line, this card does
work in my machine - but it's essential that I use the PS2 ports for my mouse and keyboard to ensure that they function.
Given how specific this issue is, I can't help but think that this has something with the way the RAIDR's legacy mode interacts with older systems - and something it should be possible to fix with an appropriate firmware update to the RAIDR. I will pass this information on to ASUS tech support as well, but hopefully this will be helpful to others (I've seen a post from at least one other person with this issue).
Next step will be installing WIndows Pro 8.1 x64 on the RAIDR - will post again once I give this a shot in case I run into additional issues.