Not really a test, but I currently have four drives on my Windows Home Server beta providing 1TB of storage. One of the USB enclosures are giving me a little trouble not being recognized after boot up. Yesterday I had to reboot the WHS machine, and the one drive didn't come back online. When going to the admin interface it displayed the drive as being offline. All share access went on as normal. I was able to access my duplicated shares without any problems. In addition, the file share that weren't set up for duplication were still there with files in them. Some files became unavailable until the USB came back up and joined the rest of the drives in the cluster.
So far everything works g ...