Along these same lines, I recently bought the Lacie Little Big Disk ( http://www.lacie.com/products/product.htm?id=10549 ) for $428 plus tax. It's got 2 500gig ESata 5400RPM drives stripped and amazingly, it gives me almost 200MB/s reads and writes! Wow, that is impressive. I an run VM's on it. I am having an issue that I was wonderig if it is a setting, something broken, or "just get use to it".
I've found that while I have high disk rates (while doing a backup or big copy), that the screen performance gets really sluggish and the mouse pointer is hard to keep track of (it lags). I know the thunderbolt bus has a lot more capacity thatn 200MB/sec, but I'm wondering if the priorities don't work so well for the video on the same thunderbolt channel.
I do have the thunderbolt port going to my apple thunderbolt montor, then to the little big disk, then to a small hdmi monitor through a display port to HDMI adapter.