What do you use for development, is there a way to develop dietpi in a virtual host such as VirtuaBox?
As it’s mostly about bash scripting, I successfully use VirtualBox VMs for bash coding and testing. There, snapshots are an alternative to dietpi-backup, but I heard that Fourdee is VMWare user, which does not offer snapshots? 
But anyway if it’s about SBC image testing, or software that kinda rely on proper hardware/firmware/drivers availability (Kodi and other video related e.g.), of course you need to do that directly on all the several SBCs, and there dietpi-backups is extremely helpful. Some of our heavier software have again several others as dependencies, downloading, installing, configuring a bunch of software from different sources (APT, self-hosted packages, git, build on device, …). You really don’t wont to clean this up all by hand to revert, even that dietpi-software uninstall does most for you, it simply takes way more time than a clean dietpi-backup recovery 
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What I am still thinking about is, besides a system backup, it would be really handy to extend dietpi-backup by some software related data/settings backup, also for server migration. Could be done via separate backup scripts for each software title (where someone manages to write the script), that were executed from main script, based on installation state.
Would be a way to integrate my ownCloud/Nextcloud migration script further into DietPi: ownCloud + Nextcloud migration script for v6.0 update