The PX4 Storm, in my opinion, is a great way to reintroduce the Cougar design with a 21st century twist that makes it more appealing to professionals and private citizens. The polymer frame of the PX4 is much more durable than the metal frame of the Cougar. Heck, polymer frames have proven themselves to be much more advantageous than metal frames in terms of durability, versatility, and ease of manufacturing.
Now, I personally do not take this claim to be absolute for every single spring and component. With my experience, I believe that they are making this claim with the assumption that the user is following a proper maintenance schedule, which requires replacing parts at certain round counts. When Beretta is claiming zero parts failure, I can only assume they are talking about the firing controls, frame, and the slide. My doubts in the absolute reliability of every single spring does not mean that I consider Beretta to be lying. It just means I am reading what they are claiming carefully and using my experience and knowledge to understand how such a round count is capable.
I believe in the PX4 design, and when I shoot my full size and compact versions against their competition, it becomes more and more obvious why I fell in love with the design in the first place. It may not be for everyone out there, but I think everyone should give it a try and see if it is right for them.