@Zeph OK by me. But I would observe that like any conversation in "the real world" it tends to branch out, and this is no exception. And things are only controversial or divisive if we choose to make them so.
@jvdk I agree with the point made by @evb , why would you want to wire connect the ultrasonic node rather than the usual radio connection ? You are adding levels of complexity and power demands for what reason ?
My ultrasonic water tank node (pro-mini+rfm69) is now 2 years on the same 2xAA batteries sending in levels every hour (RTC), the only problem encountered - condensation forming a drip on the face of the ultrasonic head during very low temperatures.
I'll try to handle crosstalk with software, it shouldn't matter if the data dumps arrive at one or the other GW. If it will pose a problem, wifi space getting too crowded or something, then it's possible to separate the gateways more so they dont interfere.