Yes, the Pandora moulds were relatively cheaply made and not finished well (or maybe it's more in the plastic injection process, I forget the details) that left stress marks on the plastic. The original ('CC') models were then painted black to hide this flaw, sprayed all over so yes in between the hinge, and the rebirth and later units were sprayed silver. Now my hinge still holds its position despite daily use (unless I shake it which has always limited its use like this), so I'm not sure how general these stories of hinge degradation are. But the Pyra case production is a much more professional operation, and paint won't be needed to hide flaws we're assured.
I'm sure replacement parts will be available on the dragonbox store, and other places. The Pandora parts were available for most of the time the Pandora was generally in stock, and I think are still available if you ask nicely.
Close-to-final cases were available for attendees at a recent show in Germany, but I haven't seen anyone reporting how the hinge felt.
I'm not sure what FBnil tested exactly, but if it was a Pyra prototype, why would you need a wifi adaptor? I've not heard of any problems with its wifi reception, unlike my Pandora, where I need to use a USB wifi adaptor most of the time. I don't know whether he was using the internal wifi, which will also have a watt-cost of course, but so will compiling big projects, or stressing a web browser.