"Actually, LED units are a lot better for sky watchers."
Is that an off the cuff remark based on your own opinion or is this a result of investigation and evidence?
The broadband wavelengths that most LED lights output directly affects nightvision. At least with the sodium lights, or at least those narrower wavelengths, you had a hope of filtering those out as it was quite narrow, plus it didn't affect your vision as much as the LED ones do.
I get the effiency angle. What I was really referring to was the lack of 'joined up thinking' regarding the entire usage and implementation.