I will write up my own "best practices for hazardous materials handling" aka miranda
When I'm a bit less busy (currently crunch time on a crazy project so I'm pulling personal overtime even during the weekend)
My profile is currently 472 MB, which is 4 247 942 messages according to the HistoryStats plugin. The method I use makes it manageable and doesn't take longer than a few minutes every week (of course takes longer if you detect an issue this way, but even so that makes it manageable since a part of it is having backups).
The gist of it is, there is a plugin called MsgExport which exports any message of any contact into a file (the format is the json format that import plugin knows how to import).
The plugin has a button that lets you export all histories for all users in your db (and it also merges users based on their nick, or manual preferences).
That way you can easily tell if someone removed you, i.e. the filename will be gone, or the file contents will be vastly different compared to that of last week (which is a full export kept for reference). For this comparison I use synchronize mode of Total Commander in "ignore dates / compare by contents" mode. There is a bash script that is necessary first due to some flags, but this method will also discover database corruption and allow you to recover it (for example partial db corruption), which for example just db backups alone will not.
It is the only reason I've not lost any user data during these turbulent times.
I'll write it up in more detail but I think this will do for a rough overview.
My miranda is my life, and the data in it is precious.