Here’s my take on this article:
I agree with this post: what to do with infinitives is a judgment call. Some observations:
In the 18th century, pundits thought English needed to be more like Latin, a “more mature” language. You can’t split an infinitive in Latin (nor in Romance languages like French or Spanish–such languages have one-word infinitives). But since English needed to emulate Latin, its two-word infinitive needed to be treated like a Latin one-word infinitive. So there. Obviously English is a very different language from Latin–it’s not a Romance language at all, it’s Germanic–so following a rule meant for a Romance language doesn’t make sense.
Second, one reason “to boldly go” sounds so good is that placing “boldly” within the infinitive creates an iambic phrase: ././ Iambic is the “natural” meter for English; it’s Shakespeare’s meter, for example. It just plain has a ring.
So place your adverbs wherever you think they create that ring. (And don’t eschew adverbs universally, either. They have important roles in prose.)