I picked up a Drobo 5D3 for a NUC (little intel compute box), powerful combination, mind you it is direct attached storage, not network. This is basically my single server that hosts “downloads”, VPN server, homebridge, a few virtual machines, Plex and backups (crashplan then out to cloud for offsite).
If you are after a simple choice that is foolproof, the drobo is a great choice. If you need advanced features and total control it is not the device for you.
I’d also encourage anyone to consider direct attached storage over network attached if most of your large file transfer volume is to a single server. Mainly due to the speed difference, thunderbolt 3 is many times faster than even bonded gigabit Ethernet.
Also using a NAS as a server can be the wrong direction IMHO as you are limited to specific software and versions, also RAM costs for NAS is rather ridiculous. But it is a more simple and streamlined approach if you can get what you need.
in the past i have been a sysadmin for enterprise organisation dealing with large scale storage infrastructure, the drobo is just fine for me as it just works without fiddling about.
Good luck with your selection and deployment, let us know how you get on.
PS - I’m hoping the commitment by Drobo to release Thunderbolt 3 support for Windows is delivered given the new ownership. Key point for anyone looking at the DAS version, you can’t currently use Thinderbolt 3, not a big deal as I doubt it would make things that much faster.