It's interesting, but I do believe that your point about Gedo Mazo is incorrect. Tobi I believe did something to stop the warping of Gedo Mazo, Gedo Mazo itself is not immune to being warped.
Also, I'm not entirely sure about "the more chakra he puts into it, the faster it warps. The speed in my opinion depends on the mass of the object being warped, and he can only warp at a certain speed. Of course, that is entirely built upon opinion I THINK.
Also, about the Kakuzu thing, if Kakuzu has his hearts out, Kakashi wouldn't have time to use Kamui in my opinion. This is based off of the idea that he can't warp things instantly.
It's interesting, but I don't honestly think that if he puts enough chakra in. he can make something disappear just like that, in the blink of an eye. Every time he's used it it seems as though it has taken some time to warp, and the larger the target the more times it takes.