Win7 64bit with DrivePool 2.1.1.561. But I did test again with the latest beta. But you have already confirmed issue.
I was in a situation of a hard drive throwing errors. Wanted to remove it, but had no more room in the case to add a drive. Nor having a spare external drive with enough space. I did have enough space on another computer on the network. But didn't want to blow away the OS. Figure I could create a VHD anywhere on the network, to limp along until a new hard drive is ordered.
I know this feature is kinda possible with Stablebit CloudDrive. But I have the same issue as others, on the forum,(see reference link below) of having I/O deadlocks. Was waiting for that to get resolved before I fully used CloudDrive.
http://community.covecube.com/index.php?/topic/1305-io-deadlock/