Ds name is unusual, it's very old and I have never met one...however I have met TWO others in my local baby group, one older and one younger than him. I am fine as it's was our only agreed name and what we called the bump, but the mother of Ds'snamechild3 looked VERY put out when she found out he was the third that year!
So only choose an unusual name if you'd still like it if it become usual.
IYSWIM