Hey All, glad to see the discussion on these cages!
My name is Andy P, and I'm a product manager for Salsa Cycles, and led the development of these new cages.
To date, there have been three versions of the Anything Cage.
V1: These worked pretty well, but they had mounting tabs that were not as strong as we liked, so we updated them to V2
V2 was launched in early 2013, and features a fully welded one-piece back plate that replaced the previous version with the three separate mounting tabs.
V3 is the Plastic "HD" version, and it was designed to address some of the issues mentioned earlier in this thread, as well as fit things like Nalgne bottles a bit better.
What you can't quite see in pictures is that there is actually a 12mm wide washer that installs in the recess for the mounting screw, and distributes the attachment load throughout the cage very well. We also added support tabs on the back to take quite a bit of the shear load off the mounting hardware as well in the event of an impact.
This cage (as well as the alloy versions) have been aggressively tested in accordance with some tough European luggage carrier requirements (and then some) and passed with flying colors. We even did a "cold condition" fatigue test on the HD version to make sure the nylon materiel we chose would hold up. Also, as a group we all rode the hell out of them for a month, and had no issues either.
My point is that these are burly, tested, and will be a great addition to your gear arsenal.
Let me know if you have any more questions!