She is about 19" at the shoulder. We have thought about it but I haven't heard good things about the reliability.

She is about 35 pounds, she will bark in a protective/territorial mode but only then. Loves to yoddle and sing along with music.

My husband and I have a 1.5 yo Basenji Mix and live in an apartment in the Boston area. The "weather permitting" part of your statement wont work with a Basenji. My dog doesnt care if its 100 degrees out or 10, she needs constant exercise. I walk her at 6 am for 15 min, my husband walks her at 830 again, then comes home at lunch and walks her for a half hour, then I am home at 330 and take her to a park for at least a half hour, then usually at least one more half hour walk before bed. If we dont do this as a minimum she begins to get really restless and potentially destructive.
My B isnt necessarily aggressive with other dogs, just not always interested. So that may mean waiting for the next elevator or going another route.
When we adopted our dog we were told she was a lab mix by the shelter and did not anticipate having this high maintenance of a dog. I am a very experienced dog owner and she is still a handful and a lot of maintenance.
With all that said she is the best dog and I wouldnt give her up for the world.