I've got a 6km link (about 4 miles). Just had some snow, and have had some really bad weather, link has been nice and stable.

I'm using Nanobeam M5 16, they aren't installed properly so the link could be a lot better, but that's my fault and not the equipment.

Check out their forum at http://forum.ubnt.com and you'll see all sorts of situations, long, short, and mid-range.

Weather doesn't seem to be a problem. There's some signal attenuation in heavy rain / snow but all I've seen is a 20% bandwidth reduction, not a failure. The one time I had failure was with a heavy buildup of snow on the antenna.