@laurent
today I ran into the same issue as the thread starter. And after I found your profile switch solution I posted it here so other people like me could find it more easily 
In my case I don't want to have the user data in $HOME/.config (linux) - because in this location I store configuration data only. The .config directory doesn't contain any sensitive data - and I want to keep it that way.
Therefore I like to have all my private user data at another location. That location is encrypted with another security key and other backup intervals (and locations) apply.
If you remove the --profile switch I have to workaround this by symlinking .config/joplin-desktop to my secure user data location. That would be an ugly solution.
P.S.: IMHO it would be better if the database location can be configured in Joplin's settings.
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