Last week I upgraded my Windows Homw Server up to the new 2011 version. So far it's good. I miss Drive Extender only because it takes forever to assign the new folders to the drives once you put all the information in them. I had backed up all my stuff to one drive and had to put it in the right folders before I could wipe the last drive and set it up as my videos drive.
I don't see any reasons to go backwards now.