I have deployed Storage Spaces in my home lab and it works quite well (Core i7 5930k, 64GB memory, x99 Motherboard). If you are going to be using it in a mirrored configuration, the performance is fantastic. In my mirrored configuration with two WD Black 4TB drives, I get ~100 - 115 MB/s during a large file copy across the network, sustained. Unless there is some kind of hiccup, it doesn't dip below. Storage Spaces will notify you when one of the drives in your array is unhealthy. Where I really notice a slowdown is when using drives in the parity configuration (simulates RAID5). Writes to the drives when configured in parity start out well, but nose dive after roughly 1.5-2GB of data moved (due to the write cache). You can resolve this by integrating SSDs into the configuration for write caching, but I have not done that yet myself.
Well, hardware RAID is in fact software RAID running on optimized separate processor. SS works just fine, running it on two servers Server 2012 R2 with 15 drives each, not a single issue for well over a year now