I think whether you do an all in one NAS/Server or separate systems depends on you.
I run in production for a very small personal business the following setup:
1 x Dell R710 on which I run proxmox & Docker ( running unifi, Active Directory,email server, LibreNMS, Webserver, Nextcloud, windows 10 VM) + whatever I want to test (New OMV version etc...)
- This is system runs 6 x 1 TB 7200 RPM disks in a raid 10 and the windows VM is on a Samsung 960 Evo M2 SSD attached through a PCI express add on card
- I run gigabit Nics and 10 Gigabit SFP+ Nics
- Dual processor system with 48 GB or ram and pulls around 200/220 watts on average
1 x OMV NAS 3.0 Build: It is a dual xeon CPU system with 48 gigs of ram with the OS installed on an SSD (I do not change a lot on this system and it runs stable)
- one storage system 6 x 250 GB SSD in mdadm raid 10 with ext 4 file system
- second storage system 12 x 4 TB 7200 RPM disks setup in mdadm raid 50 using XFS file system
- This is my main storage running SMB, NFS, Docker, RSYNC + a few other plugins (Docker runs plex, plexpy + a few other stable docker containers I use for business and don't fool with)
- I also use this as my backup for R710 and as NFS mounts over the 10 gigabit network
- Power Consumption at startup is around 350 and settles to 250 watts .... maybe slightly more
1 x OMV NAS 3.0: running dual xeon processors 24 gigs of ram installed on SSD (Oldest hardware and used as a backup for my main OMV)
- 8 x 2 TB 5900RPM NAS drives in a mdadm raid 6 with EXT4 file system
- I currently manually turn this system on once a week (can't get auto shutdown/startup working)
- System uses RSYNC to back all critical information from my OMV server over 10 gigabit SFP+
- Also has external USB attached for backup which I disconnect when I turn off the system and is kept a different location (may in the future backup directly off site)
- System uses about 200 watts when on
Basically my R710 is backed up on my main OMV1 and OMV 2 backups OMV1 with USB backing up the most critical data and taken off site.
Combining docker and full VM, I am able to run and test any other software/programs I need.
Personally having the Dell R710 lets me try new software and even test new versions of OMV without worrying about breaking my main storage array or backup strategy.
In the end I think it all depends on your power consumption concerns and how many systems you want to manage.