Like I said. Why would he have to take in more black chakra than white chakra when they are mixed together as 1 form? Bijuu Dama. By taking in Bijuu Dama he is taking in both Black and White Chakra at equal amounts, as that is what Bijuu Dama. There is no reason to believe absorption would just cause him to absorb more of one type of chakra than the other, no reason at all.Madara will have to take in more black chakra than white constantly, because if the ratio changes, 8:2, it will explode. I personally don't think he can absorb something that large with a perfect ratio, and you believe he can. Honestly neither of us is right, nor is the other wrong. We've reached an impasse simply because we can't actually provide proof for either of our claims. Hopefully you agree.
The only factor size would have is the length it'd take to absorb the Bijuu Dama. If I were to believe Preta can't absorb Bijuu Dama, it'd be because of DemonicAvenger's post, not this.