definitely has advantage over the "shredder"
1. longer tube and waterline
2. Hypalon vs neoprene
The shredder is 12'4" according to the brochure that Tom Love (the owner of Airtight Inflatables who makes the Shredder) sent me. Hyside says their boat is 12'. So the Paddle Cat dosen't have a longer tube, it has a shorter tube.
The Shredder comes in three models, two are rockered for easier turning and have shorter water lines, but the straight tube Shredder, from which Hyside appears to have copied the design, has a longer waterline. Rockered tubes turn faster, straighter tubes hold angles better - the Shredder gives you the choice of which you prefer. A lot of people running class IV-V creeky stuff will probably value faster turns over direction holding.
As far as Hypalon being superior to Neoprene - that is fairly thin ice. They are fairly similar synthetic rubber compounds. Many inflatable manufacturers use neoprene coating on the inside of their tubes and Hypalon on the outside. Hypalon is probably the better coating for the outside of the tubes, but the difference is minimal. And any meaningful comparison between them would also have to include the properties of the base fabrics that the neoprene or Hypalon coating is being appiled to. Both Hyside and Airtight have been making quality boats for decades.
If someone offered me a great deal on either boat I would go for it, but I don't think the Hyside offers any actual advantage over the Shredder. In fact with the three Shredder models you can probably get a better fit from Airtight Inflatables. My 2¢.