Juno has a really nice, sprightly sound to it. But I see a couple of drawbacks:
The old joke about "What's the capital of Alaska? Juneau. No, that's how come I asked you!"
The potential for misspelling.
It has a vaguely, space-age sound to it, like it could be a robot or a spaceship. (In fact I think it is some kind of rocket or other.)
Also, a friend of mine who went for guide-dog training told me once that when the students are first practicing their commands, Juno is the default dog name they use, as in "Juno, forward."