There’s no such thing a dumb question (except for bug reports without enough context to be actionable)
Lucee 7 is smaller and faster, so running multiple instances is also fine
With single mode, everything works as before, it’s just there are only mini web contexts per host, which basically provide webroot isolation in terms of namespaces, so app.model.utils resolves within the the current context
I have this testbed which explores / tests various single mode edge cases (all solved)
So what do you consider to be best practice if using your own hardware and multiple sites/apps? Multiple installs (seems safe) or one single? The customer will never touch the Lucee admin.