I think you're confused between radius and diameter. Radius = distance from edge to the centre, diameter = distance from edge to opposite edge (ie double the radius). Minimum diameter is supposed to be 500 blocks, but sg4 is somewhat less than this. However, there is no way this map is big enough or anywhere near detailed and varied enough to ever be a map on the servers. Its a PvP map, but certainly not survival games. Looks like a whole lot of random mess with a lot of nether brick, in my opinion. Also, breeze may not have a lot of land laterally, but the altitude differences at least makes it seem like there's more space. An entirely flat map does not feel big, so flat maps need to be quite large, as well as what i said before.