Hi Grinty,
Boy you are very knowledgable, are you a therapist?
I think you really nailed it, both OE and ODP really describe my DS6. A small disappointment and he will say it is the worst day of his life etc. and then something good he will be over the moon w/excitement (I always just say he is very emotional). And for ODP geez I could give a million examples.
Playing any game and say a pice maybe broken or a piece of lego is missing , well he will flip saying "it is ruined, it is not the way it is supposed to be, fix it, I can't play w/it etc" Disaster, game ruined day ruined etc. Or say his grandmother usually comes on Fridays if she doesn't make it one day well then Friday is completely ruined, he flips out.