1) Is it as strong as the Ferret Nation?
2) Can you split it half? I mean can you disconnect the top half if needed to only have the one l half of the cage
3) How does everyone like the cage?
Ultimately, I find the CN to be more cheaply made than the FN. It isn't put together using screws; it just kind of fits in to place, if that makes any sense. It's easier to assemble because of this, but I find it to be less sturdy. It is heavier, though, so I guess maybe that helps make up for the difference. I have both, and now that they are both put together, I don't notice a difference in quality. It was only really apparent during assembly.
You can split it in half, just like you can with the FN. A word to the wise - If you are going to have unaltered mixed colonies in the same cage, even if they are separated, you might want to invest in a set of BASS pans, or at least one for the second level, because rats can and will chew through the plastic pan and mate through the bars. I know it sounds impossible, but it's actually happened to someone who used to come on this board, and who I know through another forum I used to frequent.
I like the cage alright, and it's safer for rats, because of the smaller bar spacing. I would save yourself the frustration of modding the cage and get the CN rather than the FN. Though there is a slight difference in overall quality, it really is a well made, sturdy cage, when it comes down to it.