Finally, An Xbox 2 model being considerably less powerful than the One X doesn't make sense at all to me. I think it would at least match the One X in GPU performance, with the better CPU and possibly more RAM making the difference between the two.
I agree in general, but at the moment, I can see two reasons why they might do this, if they are doing it.
First, there's a price point they want to hit for whatever reason, and there's certain hardware that's basically necessary across both models, so the GPU TF performance must suffer for the lower end model to hit that price.
Second, if MS feels XB1X owners may feel burned by a base next gen unit that matches or exceeds theirs, by making it weaker it takes the sting away. Now that still leaves everybody else wondering WTF, but as long as the price is right and it has a worthy audience, it doesn't matter all that much.