LEDs seem to be a kind of double edged sword. Certainly in terms of energy and output they tick the boxes that local governments need to see and in theory seem like a good idea.
As far as stargazers go or more importantly for the imagers as it has been pointed out above they cover a broad spectrum and are all but impossible to filter out entirely.
Reports from the UK where there is mass implementing of new LED lights and lighting schemes tend to vary council by council. Some feel that the overall night sky is darker above and definitely less orange so it's an improvement there but at ground level it is much brighter.
Others despite all the hype of enhanced directionabilty, shielding, etc are faced with much brighter lights on higher poles illuminating their yards more than the sodiums ever did. There are some frankly scary before and after shots floating around.
http://www.rtaylor.co.uk/newstreet-l...idgeshire.html
That said they are often installed with a dimming program after midnight or better yet a complete switch off which and these plans when successful often have major benefits in addition to darker skies.
Ultimately though it does seem clear that the success of LEDs will come down to individual councils taking a sensible and pro-active approach with these new installations.
There should be no reason for these lights or any to trespass on your property and the claim they are more directional should make that possible. And if they do, complain.
That should be a first, and any council should be willing to install shielding upon request.
Dimming and switch offs appear to be the way forward as well. If for little other reason that saving energy costs but it can also have positive effects on human and animal health as well as crime levels.
I guess all you can do is keep an eye on what your local council proposes and then to keep on top of them.
