I think 6 to 9dbi antennas would be fine for me and a lot of others.
6 to 12 inches isn't that tall.
For outdoor use most people are using sectors. So I bet most of us would be using them indoors.
I have a few 5.8GHz Groove's deployed but we also get questions about a 2.4GHz version for outdoor AP (Groove A of course !!)The groove is a single change radio. (one antenna)what about Groove 2.4 GHz ? I recall hearing something about this somewhere but cannot find any solid references....