m4 is fine in production if what you're doing really is just string manipulation. It just tends to be used in cases like the one in this article, where you are

m4 is fine in production if what you're doing really is just string manipulation. It just tends to be used in cases like the one in this article, where you are manipulating structured text. In that context, you run the risk of errors/complexity/fragility because you are manipulating strings rather the structures.