With 256GB of RAM, it would be pretty awesome to setup a good chunk of it to RAM cache using PrimoCache. When I had my dual E5-2670 w/ 128GB RAM setup with Windows Server, I dedicated 32GB of the RAM to cache for testing purposes, and it worked extremely well.
I did a similar experiment with 32 x 6tb drives, 16 x 400gb s3700, and 2x 400gb nvme drives. in 4 x 2u supermicro 12 x 3.5" servers using storage spaces direct using mirroring and parity spaces. It was very performant but would have just built with all nvme drives and no ssds if I would do it over again. It turned out it was alot faster than my older storage spaces direct platform using a few dual sas jbods and 32 x 3tb sas drives and similar amounts of ssds. Definatly not an apples to apples comparison but per u of space the storage spaces direct platform performed better and with much cheaper hardware. But can be a pain in the butt to set up, though it has gotten alot easier since tp5 and forward.
One thing that I would keep in mind is depending on what os your workstations are using, a windows based storage platform can benefit you from a networking stand point. IE Windows Server networking to windows workstations is crazy fast (make note there has been a post on the forum somewhere explaining ins and outs of how to get smb multichannel working with non domain joined computers. I think it has to show network as private. long and short is just setup a domain and its all good. Bit of a tangent but may save you a ton of time in trouble shooting). I have had remote access speeds in the millions of iops and 20+ gigabytes per second from workstation computers using server 2012 r2 over smb 3.02 literally limited by the cpus ability to read and write. It is amazing and was very easy to set up.
I look forward to seeing your progress and can't wait to read more. The bigger the better!