I've been eyeing the Atrium cages too, but I've been wondering about the size. I think it's great that it gives you more width to work with and for the chams to enjoy, but it's only 4.5" wider though you lose 6" in depth. Assuming your cham doesn't use the bottom foot of the cage, I think 24x24x30 has a bigger volume than 28.5x18x30 (I could be wrong though, my math skills aren't the best). Is the volume difference enough to matter?