Not a bad idea, however I’ve had problems with some of the firmware (I think, maybe it’s the kernel) on external HDDs causing them to power off when not in use for long periods of time. For some reason it doesn’t happen with internal drives so it must be the enclosure or the way the system deals with the drive.
I’ve had the drive on my kodi box fail a couple of times now, it’s annoying. Torrenting probably puts a lot of wear on the drive though so it’s to be expected.
I have two old NUCs, one DN2820FYK with an Intel Celeron N2830, and another D54250WYKH with an Intel Haswell i5-4250U. The former can only take one drive but the latter can have an mSATA as well as a 2.5" SATA. I’d like to use the latter with root on the mSATA SSD and a 2TB HDD for media in the 2.5" SATA, but for some reason I get better video playback on the Celeron than the Haswell. Both are supposed to have hardware acceleration for h264 and the Haswell is a more powerful processor so I don’t understand it!
Did you not switch to Nextcloud a while back?