I'm accustomed to using Patrick Gaskin's
kepubify tool for conversions; I even wrote a barebones Calibre plugin to let me run it on epubs in my library and import the resulting kepub.
Now I see Calibre 8 has a kepubify feature built in, but it is built from scratch in Python, rather than using the existing kepubify tool.
How do the two kepub conversion tools compare? Is there any reason other than convenience to use Calibre's tool?