By the way, there is a scenario that is sort of best of both worlds in regards to speed vs convenience using a NAS, and that is to write your own localisation scripts. But this obviously gets a bit technical. I have done this for my own setup, where I have a QNap NAS and three machines. Then when I grab a file from my network drive, a process localises the data to the machine.
The same thing happens when I submit a render through Deadline, where my rendering machines localise the data for the scene, before they begin rendering. There is a smart check to know if a file needs to be updated before copying the data to mimimise the amount of network traffic.
This has saved me a lot of time and hassle, with only a small amount of overhead for initially localising the data. But again, the key here being able to have the ability to build a script/tool to do this.