Truenas is good. You might need to tinker with it a little bit for setup... but you do with a NAS as well. It's pretty much NAS software on a PC.
For $800 I'd build a nas... it'll always be better!
We have 10ish people in the office - Typically we have 2 graphics artists accessing / writing files, sometimes large ones. 2-3 Sales reps doing light tasks such as writing up work orders (Excel files) CNC operator...but also small files, and an accountant doing excel stuff. Not too much access at once.
How much space do you need? I'd use your $900 and buy SSD's... You can get close to 10 TB of SSD Space with that, then run Truenas. do you have a crappy old PC around? Throw truenas on it and play with it before committing... its super simple!
We've been hit by ransomware 2X now... Our old IT company has the office setup in a stupid way that keeps us open to the outside world - they assigned a domain admin account to our accountant... Who keeps somehow having his account compromised (He clicks lots of bad links...) And then every single PC thats turned on gets encrypted... Wasted dozens of hours on it. Currently re-setting up our whole network... so I've been looking into truenas a lot.
so I'm very, very anal about backups... Right now our accounting software will Zip up everyday at 6 PM. Then it'll back itself up to google and a remote server. Then it'll back up the artwork (about 7 TB) To google, and a remote server. I also have it realtime syncing the art room folder... So the moment an artist saves a file... it uploads to google and the remote drive.
I have - Weekly full backups (saves a months worth) As well as version backups that save every night.
I had to do a restore and it took 3 days to restore 7 TB From my remote server to my NAS... I did a test and restored it to my server instead of the NAS and it took a few hours. The NAs has to process a lot when it's doing a restore, and the CPU in the nas sucks.... just using it as a file server isnt bad, but if you ever have to restore a drive....thats where it gets you.
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Celeron+J4125+@+2.00GHz&id=3667 This is the CPU in the nas you're looking at - And I'd say the 920 is one of the better nas's. CPU score isnt always the best to tell... but itll be good enough for a comparrison. 3000 CPU score... comparing that to the latest, cheapest AMD 7600X which costs $340
https://www.cpubenchmark.net/cpu.php?cpu=AMD+Ryzen+5+7600X&id=5033 28645 score.. Almost 10X Faster. Ontop of having more ram to handle more tasks / multitask. To me.... using a desktop as a nas is better for futureproofness, being able to have more hard drives... its cheaper, And runs smoother. The only benefit to using a synology vs a truenas setup is it eats up 1/10 as much power.... but we're talking like $10 a month, for a business thats nothing.