I would only use good, new equipment and have to find a space-efficient case with the drive bays.
Now I have some timed results for a relatively simple task.
In a folder with 2000 RAW files (124GB), the times for thumbs to fully display in BB are NAS=301 sec., Hitachi 6TB 7200RPM NAS drive=197 sec., and SSD=185 sec.
The NAS is slow, but not too bad for GbE speeds. However, the times to extract all the jpegs (not a CPU intensive task) in BB are NAS=21.7 min., Hitachi NAS drive=7.4 min., and SSD=5.3 min. Obviously that NAS is sucky slow. Anything that requires a lot of reads then writes like working with the panos would be terrible. The real concern I have is if a good 10GbE NAS will solve all the problems or not.