Just a quick update:
Came to my nan's today, after a week or so, so I'm back on my MBA.
I can say, without doubt, that the keyboard on the Pro feels more solid.
Display is still beautiful on my Air, and funny enough, I think I actually prefer the smaller screen! I have apps set to take up the entire screen (not full-screen mode) and everything is good. I just use a Hot Corner to activate Mission Control, to switch between apps. Sure, the 16" is big and beautiful, but I think I like the size on my Air better? Just set the size, and forget.
Speakers, the Pro is on another level.
Pro-Motion: To be honest, can't really tell a difference? Maybe I'd need them side by side to see it?
The MBA is so much more portable, so if that is a big factor for you, I'd go with the Air.
Anyway, hope this helps someone out, who's on the fence.
Any questions, feel free to ask.
Wishing you well.