Here is a really simple way that we look at these scenarios. Do you think that you will all walk away, then precautionary. If you have some very good reason to think you will not walk away, emergency.
Here is a neat brief for the Cabin Manager;
N - Nature of emergency/problem
I - Intentions (eg circle back to land)
T - Time remaining/estimated til landing
S - Special considerations (numerous)
It works for me.