But under the hood I think it uses a better algorithm. In my experiments it reports pitch faster and more reliable and stable than fiddle~. So if you can use sigmund~ I would recommend it over fiddle~ as a replacement.
Back in the LAC 2008 in Cologne, I asked Miller that very question: what is the difference between fiddle~ and sigmund~. He said sigmund~ was the best pitch tracker he had programmed so far. So I guess fiddle is still alive just for compatibility reasons.
alabala