Aero refuses to install #10 zippers even on their heaviest hide jackets citing period-correctness. #5 zippers are not up to task on the heaviest hides Aero is using. They were okay on thinner hides from the period. So that is what's wrong with Aero zippers - wrong hardware is being installed. Hope that answers your inquiry.Ah, I was a bit confused why you wondered if I quoted you.
You said: "Personally, I have been avoiding Aereos due to their terrible zippers."
That implies they exclusively offer bad zippers, because otherwise you would surely specify one that wasn't "terrible" when placing an order. There was no caveat in your sentence, that may have suggested you weren't talking about "all" their zippers.
Edit: Third time lucky: What goes wrong with your Aero zippers? I'm merely trying to ascertain what it is that fails on them? The only zippers I've had fail in my life were on cheap luggage, so I'm having a hard time picturing it. Or is it like the other guys said, and the zippers are poorly attached to the jacket and pull away? (More an issue of construction than a zipper issue, that.)