Combination of Storage Spaces and Dynamic Disk RAIDs
It doesn't make sense to combine several mirrored virtual disks created in Storage Spaces to a RAID0 using Disk Management, Dynamic Disks, and LDM as described here, at least when dealing with not too many disks. Apparently, too many is more than eight disks. If you have eight disks or less, the Storage Spaces driver allocates data in such a way that you get a RAID10 consisting of four disk pairs maximum. It is pointless to impose one more RAID layout on top of this configuration; doing so you can even make the matter worse due to alignment issues.
Talking about alignment, it should be noted that stripe on a Storage Spaces virtual disk is 256 KB in size and starts from the beginning of the virtual disk.