What I keep wondering is, given that whole "when a great wyrm roars" thing, wouldn't Bahamut angry rampage have caused some effect with Dravanians and the dragon star? Elder Primal or not, he was still the "Dreadwyrm." And you heard that deafening roar at the end of Praetorium.

As for Midgardsormr, I'm starting to think he's on the level of Hydaelyn and Zodiark (and the Cloud of Darkness).