@Robb +1 I share all of your points.
- Way overkill configuration for SMB purpose.
- PSU efficiency
- RAID choice
- last but not least, hard disk choice: reliability does matter here
I would add that if performance matters (and I suppose it does given huge configuration you expose here), I would install system on SSD and keep your standard disks for /var and data.
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"I'm riding Ducati 750. Is it OK?"
well, it depends on what you intend to do with such a motorbike... if you see what I mean