Thanks that's very helpful! So you'd recommend the QC25s then over replacing the QC3s? I liked the rechargeable battery that the 3s came with, not massively keen on an AAA battery. I'm not in the US for a bit after this week so I think I might just pick up QC25s from a shop today (a bit cheaper over here), assuming I'm not going to see the ones I left on the plane again...
Tried calling ORD but unsurprisingly no answer seeing as it's 4th July. Will try Sunday/Monday and report back for future people in the same boat as me

Fingers crossed.