I think the passive awareness trapping is more broadly useful than the other stunts like stone-cunning.  It can be used to avoid ambushes, make declarations and assessments in more situations.  It's one of the most used skills/trappings, I think.  Really, the only thing the trapping doesn't do is determine your initiative.  If it was the +2 passive awareness when spotting an ambush or >>insert some other condition<< then I'd say it would work.
But that's my opinion.  People may disagree.