Gas system is a relatively inferior system because #1 & #2 still holds but now you need an uncle in refrigeration business because freon 134 (1,1,1,2 tetra chloro ethane?) is very expensive, and sooner or later it will be banned too because it still harm the ozone layer though not as bad, & it worsens the green house effect & Obama doesn't like it!
And the environmentalist might start picketting at your RC submarine meetings[X(][X(]
The worst of all is that your fresh fish from the pond will arrive semi-frozen