I'm not convinced with Storage Spaces...
You can't remove drives once they're added to the space - without moving your data off, deleting the space and starting again. DE did this really easily to allow you to add and remove drives.
In a Simple storage space (no parity or duplication) files are split into 256MB chunks effectively making your Storage Space a large RAID0, if one drive fails the whole lot goes. DE stored full files (and often folders) on a single drive that could at least give you some chance to recover at least some of your files.
Finally, whether it's a beta bug or not - I'm not sure. But I had a problem with some disks not liking my controller. Windows would start to create a storage space and they would time out. After that Windows (WSE2012) would BSOD everytime one of those drives were connected - and wouldn't even boot. I had to manually clean all the drives that contained any remnant of the storage space.
So far Storage Spaces is a brilliant idea, but still not as good in some respects as DE, and given the problems I've had with dropped drives I won't be trusting my data to it just yet.