As an oddball home Ruckus user, I have abused meshing across buildings like this — mainly to extend my apartment's wifi network across into a fitness center about 50 feet away. And in fact, I am using 2 7982's for this purpose.
As Michael said, having the height line up is key to getting good meshing range out of this arrangement. The gym is 3 floors down from me, and even using a vertical dome-toward-window velcro mount of the 7982, the mesh link only runs at about 10mbit for me, but that's plenty for streaming workout music.
As an experiment, I was able to go to the 3rd floor of the apartment building across from mine, and established a mesh link double this speed. Definitely the height line up makes a big difference. The vertical vs horizontal mounting orientation made less of a difference than I expected, though.
All in all, it works, but I'm streaming music on a treadmill and if I had an enterprise customer, I would rather they use hardware built for this purpose 🙂