The general manager responded to my post and pointed out that the first production run used a fabric treatment that left the uppers somewhat brittle. This is very consistent with my first impression of the shoe – the fabric seemed somewhat stiff and thin – and (with hindsight) probably prone to tearing.
I'm going to take them up on the offer and exchange them for a different pair with the new uppers and will report back. I hope they work out – as I really want to keep these shoes!
You can read the full response in the comments section of my previous post.