Check out this article on SAN, NAS and SQL Server. Older but still relevant:
http://www.perftuning.com/pdf/MSSqlSAN.pdf"the main issue with NAS is that the path that the I/O must take typically is much longer than that of a SAN. This is due to the fact that the NAS has network protocols involved that must be processes as well as filesystem overhead. So, in a NAS
environment in may not be possible to achieve 10ms I/O accesses, depending on the NAS. This might adversely affect your performance."
A NAS would probably be OK with a Gigabit ethernet network in a small office but you need to be sure to buy the fastest NAS and drives you can and pair it to a fast Gigabit network. Testing would be required before implementing in production.
