If it's not a need for speed, I'd reconsider the NAS options and go with Synology. I have a 12-bay and use their own more flexible RAID-like setup instead of RAID 5 and find it great.
The challenge with DAS RAID especially using HDDs is the "unexpected ejection" bug(s) in macOS. If you know nothing about it, it's an effect like you've pulled the cord or detached without first ejecting the enclosure in software. You get the warning on screen about the unexpected ejection and it usually takes actually disconnecting if not fully rebooting to make the DAS available again. This can feel random, occurring in minutes or hours or days and often gets spun as <blame everything but Apple> redirection, something is wrong with only YOUR system or enclosure (also redirection), etc. by Apple fans. But if you search for the problem, you'll find abundant posts by many people with all kinds of configurations, cables, hubs & direct connect, Silicon and Intel Macs, etc both here and even on Apple's own support forums.
It's been a problem for now 4 generations of macOS, meaning if you take the same unexpectedly ejecting enclosure with same cable and hook it to a pre-Big Sur Mac or ANY PC, the enclosure magically "just works"... basically screaming where the problem actually lies. It doesn't affect all enclosures, so it's like a game of lucky chance: this one may work while that one won't.
More
objective Mac users tend to think the problem is tied to Mac sleep- and there does seem to be something there- but I've had unexpected ejections
while actively transferring files to/from a HDD RAID enclosure that works fine on pre-Big Sur Macs or any PC... so definitely not an exclusive source of the issue as neither end can be asleep during active transfers.
I
suspect power management code from Silicon roots that hasn't been updated for Macs not necessarily dependent on maximizing battery is to blame: basically working the power draw of the attached enclosures down to "max battery life" (that may not even be in some Macs) to the point where it falls below some key minimum threshold for the enclosure and thus causes the unexpected ejection. I think sleep gets the blame because that would obviously be a time to minimize power draws in iDevices & MBs but also because sleep is often for hours or overnight, which offers abundant time for a random-chance unexpected ejection to occur.
A software remedy that seems to help
some is apps like the one called
amphetamine, which basically keeps the attached drive active/awake 24/7... at the presumed cost of wearing out the RAID faster than it would if this part of things "just worked" as it used to with macOS.
This problem also exists for SSD RAIDs but
seems to not be quite as broad there. It is NOT a Silicon hardware exclusive as there are many reports of Intel Macs working fine with enclosures pre-Big Sur, upgrading to Big Sur or newer and crashing into this problem. In some of those cases, users needed a reliable RAID more than they needed new macOS features so they went to the trouble of downgrading again, which made the RAID resume its reliable usage... again screaming where this problem lies... because all of the variables usually blamed in redirection remain the
same.
I've essentially got a perfectly good RAID DAS in temporary retirement... awakened with each macOS upgrade in hopes that Apple has finally got around to debugging this part of macOS. So far- now years later- no success. Take it over to any of my older Macs still running pre-Big Sur and it works as good as it ever has.
The hopefully-temp substitution for me has been a big single drive DAS but that's limited to capacity of single drives: 24TB for HDD and 8TB for m.2 SSD. I keep hoping the RAID DAS I have can come back into active use again vs. choosing to try enclosure after enclosure in search of one that can remain reliably connected. Hopefully, if you plow forward anyway, you will discover one that WILL not have this issue... and/or someone will recommend one they know for sure does not suffer this issue because they
have and use it... not just reading about possible options on web pages. I look forward to seeing if there are some dependable ones available that fully overcome the unexpected ejection bug. I'd like to have access to my RAID 5 again myself.
All that offered, my Synology NAS has never suffered from this problem. It doesn't offer the speed of DAS RAID 5 with many drives, but it does offer dependable big storage in- IMO - a better-than-RAID 5 setup.
I hope someone can identify a solid choice they
know will be reliable and/or you just take some plunges and discover one and report back.