pitch~ or fiddle~, that is the question...

MIT has some externals called pitch~ abd fiddle~.
I am new to doing realtime pitch detection. I was wondering
if someone could give me some tips on using these. Of pitch~ or
fiddle~, which is better? If I had a prerecorded snipet of the
instrument I was going to interact with, is there a way I can do
some spectral analysis to help train pitch~ or fiddle~?

Anthony