Really good questions and ideas here. I’ve been trying an experimental feature to keep both Urgency Load and Total Buffer on my dashboard:
But alas, without actually beeminding it, I’ve just become banner-blind to it! 
So I still don’t know which, if either, I’d expect to be more useful.
I guess this means I need to try beeminding it! Ok, here I go:
As for whether Urgency Load and/or Total Buffer should account for autoratchets – also not obvious! (Reminder to ourselves that making it a setting because we don’t know which choice is better is a classic red flag.)