Thanks for your input.
ad 1) I have two 3.5 HDDs (Seagate IronWolf). But primarily used for backups from our PCs. While I don’t have concrete measurements, I assume the NAS is idling more than 90% of the time.
ad 2+3) Not a big deal, but rather an inconvenience since I have to reinstall the base system and packages but can use the configuration backups. So this is a nice to have.
ad 4) Actually, I hadn’t thought about this before. The main concern is that my NAS currently remains mostly idle. Running Docker containers might prevent it from idling, raising the question of whether I’d need to migrate to SSDs to reduce power consumption? This would double the migration costs (two 4TB SSDs for both the current data and the additional storage for Docker containers).
Thanks for the input. I initially came across lower power consumption estimates for the N100, approximately 5-7W, but I now re-checked and indeed some people report idling at around 13-15W. I guess a lot depends on the peripherals and the quality of the PSU. But such a slight improvement wouldn’t be worth the hassle