I've ran a tropical tank with airstones for circulation(regular return though) and am still running a coldwater tank with airstones.
They are great since they produce a lot of flow that is still very gentle, they also have no intakes that can trap and hurt fish or invertebrates. They also don't clog... Well, they do get covered in time but that takes a long while. I got them in the first place because I was trying to grow kelp in the coldwater tank and my streamers caught so much hair algae in a few days that the flow stopped. They also add no heat to the water, or close to none. It is also quite efficient. A 20w airpump can drive a pretty large tank, at least 50 gallons(ca 200 liters). It can make a tank half that size boil with flow. Since you often install the stones on the bottom of the tank water is circulated though the entire column.
They have a very nasty habit though that made me remove them from the tropical tank after a few months... Salt spray. To use them in a tank without a glass lid is more or less a nightmare, and the glass only helps, it does not eliminate the problem. The bursting bubbles pops salt everywhere around the tank. It ain't that bad in the beginning, you can wipe it away with ease but with time it starts to collect in weird places you missed and then the white horror begins. Once you start to see salt crystals somewhere around the tank that area is infested and will continue to torment you.
It is also noisy. Not much mind you, it's fairly quiet compared to many mechanical pumps. But it can never be truly silent unless flow is minimal or you have a tight canopy that insulates. The bursting bubbles always makes sound. Might be soothing to some but it is still sound.
In my coldwater tank the creep is much less of a problem though. The cold water actually helps a huge deal. Since it is lower the splashes from the bubbles actually flow down into the water again instead of evaporating leaving the crystals behind. You still have to cover the tank and some spray does still occur but the difference is dramatic. Here the advantage of not adding heat to the water is also much more important and makes a significant improvement to the temps. Which is good for both the inhabitants(slower temp fluctuations) and the electric bill(chiller runs less often).
I do believe that with air lifts you could create a degassing chamber which would remove a lot of bubbles which might make air driven tropical tanks much more feasible. Will experiment more with this...
