I'm thinking of getting the Air. My 16PM is annoyingly bulky.
Battery life- seems like plenty for my daily usage. My 16PM is way over the top. The only times I need a lot of battery are when attending events or visiting places where I need to take lots of pictures/video or use maps/navigation, but these instances are very occasional and predictable so I can always bring a MagSafe battery along.
Single speaker- I don't care at all about stereo speakers on such a small screen device like a phone. I just want the speaker to be front-facing, which it is. I do kind of care about max volume, but it should be fine since the only time I go even near max volume on my 16PM is when listening to a podcast while showering, but I can also just use my BT shower speaker.
Single camera lens- this is my only hesitation since I often use all three lenses on my 16PM. But I've been considering getting a good dedicated PaS camera with more powerful zoom. If I can comfortably front-pocket the Air (front-pocketing my 16PM feels uncomfortable and looks ridiculous to me), then I can carry the dedicated camera in my cross body fanny pack which I wear anyway because I dislike pocketing my annoyingly huge car key fob and my wallet. I can tolerate pocketing them (and actually I hook my keys to my pants belt loop when I need to), but it's my 16PM that I can't stand pocketing which is why I have the fanny pack.
Moving my phone from my fanny pack to my pocket will will give me the option of leaving behind my fanny pack on occasions where wearing it is inappropriate or impractical or I just don't feel like it, and if I know I won't need my dedicated camera, in which case I'll pocket my wallet and keys.
So my next steps are I need to check out the Air again and try it in my front pocket, then I need to see if there's a good PaS camera I want.