I doubt anyone was under the mistaken impression that USB flash drives have better read and write figures than SATA drives.
Me, too, neither. Merely trying to point out that there are tools to verify or disprove whatever we think.
Also makes me wonder what the hit would be compared to an old noisy IDE drive.
I built a server rig at one time which ran a small server from a USB drive - live.
Made room for an extra HDD for the server and ensured the OS would be back to pristine after a reboot if anything untoward were to happen.
Well worth the effort in that case as I recall.
Would probably be suitable for a firewall also.