The question was not much about "new release" posting, more about spreading the word about a new project. And news could be written in a more "creative" way.
I asked the original question because a one shot news will not necessary gets "enough" attention, depending on the time or the day it has been posted for example.
I've been a long time and happy user of Launchy. It's a great tool and you might have noticed the small tribute to it in Keypirinha by using the term "Catalog" to name its internal database :)
Keypirinha is more modern than Launchy in many ways and integrates better in recent Windows platforms (for example I've had troubles due to 64-bit platforms with Launchy; items not found or not launchable, ...). The search accuracy is very much improved as well. You can have machine and/or user-specific configuration in a portable way. In addition to that, Keypirinha is more easily extensible, it embeds a Python interpreter to load its plugins (whereas you had to compile a C++ plugin to do the same job with Launchy; I wasn't happy with the unofficial Launchy-Python plugin). That gives the user the power to modify the existing official plugins (they are open-source), or to create new plugins that fit her needs (that slowly leads us towards your "searching scope" question).
Keypirinha is also very young compared to venerable Launchy so its plugins catalog has yet to be "flourished".
Hope that answers your question regarding Keypirinha vs. Launchy.
Wox offers more exotic features, but to be fair is also way less efficient when it comes to search accuracy, speed, memory footprint and battery friendliness.
Different purpose. Everything rocks at finding files and is complementary to Keypirinha, which rocks at adapting to your needs. As explained in an other comment, Keypirinha is way more than about launching apps and documents.
Incorrect! You don't get the benefits of Keypirinha's scoring system, which makes it far more efficient than Windows' native feature.
Also, if you wish to perform more exotic tasks like launching a PuTTY/FileZilla/WinSCP session directly, you would be on your own.