Using a slave pin still requires compressing the spring into place prior to inserting the slave pin, This captures the spring allowing it to be pushed into place without risking having it flying off into space. No need to use a slave pin, it makes replacing the trigger spring a 2 minute job. As I said IF you shoot competition with different CZ's it is a time saver, for one or two Cajun installs not a big deal.
FOR ME not having to pull the trigger up far enough to use the slave pin makes it worth it, just push the (Cajun Gun Works free floating) pin part way out, remove the old spring and in with the new, DONE.