Well, after looking about at other possibilities, I have installed WHS RC and am trying it out. My usual backup service, Mozy, is pricey for the essential server backup so I signed up to IDrive which is working well.
I have only got a 500GB drive for the server to use (it has a 320GB drive for itself) and installation seems to be quite easy as well as getting machines connected. I can't use the built-in backup to backup client machines due to lack to disk space but it doesn't seem hard to do. We will be putting some data up in the preconfigured folders and see how things go.
My plan is to get to final release version and put some 2TB disks in to cover the data and client backups. By then I will know well it works. It would be handy to have drive extender but with very large disks managing disk space shouldn't be too hard. You never know, DE might come back in the next version!