It’s strange that the Joomla! extensions directory indicates that Rapid Recipe is GNU GPL licensed, and yet a commenter on that site (and your post) indicates the the source is encrypted and IonCube is required. That seems to be a inconsistent with the program’s licensing.
I don’t think I would go so far as to say you are “about to be a fool”, but I do not like the idea of using encrypted code at all on my sites (and I don’t/wont do it myself).
One site I “manage” does have an encrypted component installed, and it has been nothing but trouble from the very beginning. You are completely dependent upon the developer at upgrade time; and should some other component you install conflict with it, your only recourse is to contact the developer and hope they can patch/fix the problem.
Have you looked to see if there is any truly “open” software available that might also meet your needs? Even if it doesn’t do exactly what you want, you could at least modify the code (or have someone else do it for you) and retain complete transparency in your code.