In another thread recently, someone mentioned that Phoenix wasn't a good name choice for a project because its been used so many times. I feel like Onyx is the same way. This thing might displace the other Onyxes for a while only to be lost to history when some other software project eventually is also called Onyx.
As long as Onyx is easily searchable while it remains relevant, I don't see this as a problem. Yes, this particular incarnation of 'Onyx' might be lost to history after it has stopped being relevant. So what?