For some of us it's a financial issue. I already own a Raspi 4, but don't have money lying around to get a decent mini server (e.g. acceptable performance paired with low power consumption and no fan noise).
I still manage to run a few Docker containers on top of OMV, but need to be mindful of the load:
- Jellyfin (no transcoding)
- Immich (workers set to minimum)
- Backrest (restic frontend)
- Duplicati (phasing out)
- Heimdall
- changedetection.io
- Tailscale sidecar containers
But yes, when running a bigger backup job, I pause Immich indexing or shut down Jellyfin, just in case
Jeff Geerling ran some benchmarks on USB storage options in 2020, including a pen drive SSD: https://www.jeffgeerling.com/blog/2020/fastest-usb-storage-options-raspberry-pi
Das ist wie mit der Bohrmaschine. Die muss auch ein paar mal durchgestartet werden, bevor es losgeht
I also use those, but (shame on me) I've never tested the backups. Have you ever restored such an image backup?