Since pictures are worth a thousand words...
Here's two Evernew bottles rolled up and secured with the fancy pants orange shock cord. This is how I would typically store my bladders in the side pocket of my pack. The one on the left is the handy 2000ml bladder and the one on the right is the 900ml. Both of these are roughly 4 years old. The larger bladder on the left is the one that failed in normal use from the shockcord "cutting" into the sides of the bottleneck while rolled up in my pack. Sure, it still holds water, but leaks like a sieve if not perfectly upright and/or filled up.
Closeup of tear on one side. Both sides were torn equally.
Delamination where the bladder meets the rigid neck opening.
So, my point?
The claimed durability isn't really all that great, at least in my case, not enough to be claimed the "toughest" IMO. But what do you expect from wafer thin polyethylene? The flexibility of the polyethylene will noticeably diminish in a good season of use, as with any of these "Platy" style vessels. I live in NM and it's dry, dry, dry. Maybe the heat and sunshine played a big role?
Something to consider if you have $12-$15 burning a hole in your pocket. That's at least a sixer of Oskar Blues Chub and a whole lot more fun.
Sorry if I hijacked your enthusiastic post Travis, just thought I'd bring everybody down a notch to my crotchety level tonight. Of course, YMMV with the Evernew bottles. One example of a failure doesn't mean they're garbage. Ben is right on, exercise common sense and care, and of course there will always be the odd lemon in the lot.