GrapheneOS has a full system backup, but I haven't used it yet.
Having access to all data feels great, but I personally used it only once: to move history and open tabs fom one firefox fork (Mull) to another (IronFox). It came very handy tho.
I completely agree on the system tweaks part.
And for an adblocker, I wonder what do you use? It was a big reason to root for me, but I switched back to RethinkDNS (DNS blocking using the VPN slot) after a while. The reason was that I use pretty aggressive filters, and need to unbreak apps often. With ADAway, I needed to start logging, then do the problematic request again, look in the logs, allow the domain, and then reapply the filters to my system.
For blocking individual apps from accessing the Internet entirely, I couldn't find a good solution, although I feel like it must be possible with root. GrapheneOS, on the other hand, allows you to toggle the internet permission like any other.