Giri Saturn (the commercial version of Giri Giri) was simply amazing back then... That's why there were so many hacks of it by people who wanted to be famous. The first person who hacked it and made available to the public was the only person (apart from the author) that deserved to be credited. Every other person that "hacked" it again (especially Barnito and the Cassini team) were just lamers who wanted to be credited for the work of others without making any essential changes to the emulator itself (like adding good looking installers, changing the name of the emulator, the name of other files as well as including tools and info of other authors to the installer and naming them as their own tools and info).
Regarding the "open source" stuff of Cassini... It's just ripped assembly code that has absolutely no real use (you can't make essential changes to the emulator using this piece of code). The only person who is able to make such changes is the original author of Giri Saturn.
Nowadays, the best Saturn emulator that manages to include speed, compatibility and accuracy is SSF with the private BETA of Satourne coming second. Giri Saturn (including its hacks like "Cassini") is in the third place right now and since it's not developed anymore it will fall even more year after year...