Be careful about AU 6.3. It could not find my AEBS, at least in its main window. I could configure it by going to File/Configure and entering the IP and password, but it just spun its wheel looking for it on the main window. The download page says it is for N and AC base stations, though.
Hang on to the 6.2 package if you have it. I deleted 6.3 and reinstalled 6.2.
This doesn't bother me too much, as I use AU 5.6 on Lion and AU 5.6.1 on ML to do my configuring with.