I like my FN. For me, it's super easy to clean and I love the full access to it. Unfortunately, I bought it before the critter nation came out, otherwise I would have ditched the FN like a hot plate and gotten the CN that has the 1/2" bar spacing. I'm on a college budget, though, so the FN stays.
do you think this cage would work? Because I have the same cage but bigger
What are the measurements (LXWXH) of it? If you do purchase it, I would make sure you cover those levels and ramps with either fleece or some other material to protect your rat's feet from the mesh wire.