Go ahead and measure the spindles on an Apex and Rx1, you'll find they are different. Along with the Deltabox, the suspension, the seat, the engine. There isn't much that wasn't changed between the two.
You can dislike Yamaha all you want but you can't say they haven't been a leader in development. Some good, some bad but pretty good considering the economy here and in Japan. Weather etc.
They started the whole 4 stroke thing which every other manufacturer figured out EXEPT Poo who's attempt was a disaster - remember the FST? A sled truly made by farmers for farmers! LOL
They did the 3cylinder RS line also which after the RX1, then the Apex line came out, then the 3cylinder went into the Apex chassis. All big programs because they went to ful injection which was basically new engines..
Then the Phazer came which was another new concept in sled design, and after that the Nytro.
I agree the Phazer and Nytro were poor designs but they went there and tried, a lot like Poo with the Fusion. Another great Polaris design. So the AXYS didn't just show up, Poo had a couple failures to get there.
That's why I think Yamaha joined up with Cat on the Viper. They went down the path with the Phazer and Nytro and it turns out it was a bad decision and left them with nothing different in the works so it bought them time to change direction. And through this they still continued to upgrade the Vector/Apex line.