[Fyron]

There are the same number of methane worlds as hydrogen, oxygen, and carbon dioxide. The bug is that there is one more methane rock world than methane ice world (or was it the other way around?). There are the same number of methane worlds, they are just not balanced between rock and ice as all other atmospheres are. This is so inconsequential that it really doesn't provide any meaningful benefit though...

Other than none, the atmospheres are balanced. None has fewer facility slots overall, due to the lack of gas giants and tendency towards tiny planets (moons).