I totally agree with you tkaiser.
As I have been using the rpi3b+ as this was the best at the time I made a NAS for testing and it have been running since then. But with this hardware I always had to do workaround for large files.
I will give for this idea. What about the Platform to be used with the proposed hardware? OMV lacks web-based file manager like the Synology DSM. Do you have anything that can get the work done as web-based file manager and not the ftp style one.?
Also I found helios which is the same idea as yours but low performance CPU.