[dogscoff]

Welll, only that there are lots of lovely atmosphere- free moons everywhere to colonise. On the other hand, large and huge breathable planets are quite rare when you take atmosphere and acquiring gas colonisation tech will be a bit of a disappointment, since you can't have an atmosphere free gas giant.

Oh, and you aprobably won't have much competition for breathable planets from other races.

By and large, the various atmospheres and planets types are pretty well balanced.