After reading a lot about REFS and the Storage spaces it sounds better and better.
Currently I have a G-Speed Q with 12tb at RAID5.
I have read numerous horror stories regarding RAID5 for small arrays.
Articles like this have been floating around for a while.

http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/

What is the consensus about the best solutions for large persistent local storage?

Well largest I recall was one of our customers doing a recovery on 150 or so drives in a single pool. Storage Spaces with ReFS. Took them two to three months I recall. The Storage Spaces pool has the same RAID5 inside it. The RAID5 is limited to 8 columns max, no matter how many drives, and this somewhat improves stability. However, the overall complexity of the system introduces some arcane failure modes, with a good chance of not recoverable.