The Qubes backup system has a security feature that most other backup options lack: authenticated encryption. When you need to restore from a backup, you may think the file you’re restoring from is your backup file, but what if it’s not? What if an attacker has replaced it or maliciously modified it in some way to attack your system? The Qubes backup system is designed to protect against this, allowing you to safely restore from backups in dom0 even when if your backup file has been “in enemy hands.” I’ve described this a few other times on the forum, e.g.:
Yeah, basically you should back up everything that would be impossible, too difficult, too costly, too cumbersome, too time-consuming, etc. to recover or replace, and not worry as much about backing things up that are easy and cheap to recover or replace. So, if your templates can be completely recreated from some notes that you have backed up, then perhaps the only reason to back up the templates themselves would be convenience and time savings (i.e., being able to restore from the backup instead of having to go through the recreation steps), or for the sake of redundancy (e.g., in case your notes turn out to be wrong or missing something). For most users, it probably isn’t a big deal if they forget to write down that they installed a certain app, since the next time they needed it, that need would remind them of it, and they would install it at that time. In such cases, the stakes are relatively low, so there is not a great need to be fastidious about it. The higher the stakes are for you, the more effort you should devote to this stuff. If you can’t afford more than N hours of downtime, for example, then by all means, back it all up.