Well, depending on your hardware setup, you can certainly get some pretty epic performance out of it.
My specs:
AMD Ryzen 5 1600
MSI B350M Mortar Arctic
16Gb DDR4 @2100Mhz
Nvidia GT750 (Because Ryzen won't boot with graphics card, not used for anything else)
2x IBM ServeRAID M5110 (Only one in use at the moment)
1x Intel 540 series SSD
2x WD Red 6TB (WD60EFRX)
2x Toshiba 6TB (MD040ACA600) - Don't get these, they blow.
4x WD Red 4Tb (WD40EFRX)
Custom chassis built into Ikea Hol box
I have Rockstor root on the SSD, and primary pool as RAID10 on the rotating rust.
With the above, I can stream 4K Plex while downloading at my max DL speed (which is admittedly crap. ~3.5Mb/S), also constantly storing and processing CCTV footage. Typically I never go above load avg of around 2.
While I highly recommend Rockstor, if you do go down this path, be ready to tinker. The stable branch is for the moment bypassing testing and has been known to break things on update.
There is a lot of community support here (Myself being one of them, I just use the thing, I don’t make it), but questions can sometimes take a while to answer, or remain unanswered if nobody knows the answer.