This raises the question of how the logos and the Son connect to each other. Which is first, which is second? Which is subject, which is predicate? Which is the name, which is the attribute? Which is "real," which is "metaphor"? Of course you can reply "both" to every question, but I think they are worth asking anyway. The basic issue being, does the Johannine logos describe the personal incarnation of something impersonal (the "thought" of God, for instance, as revealed in Jesus) or the impersonal qualification of someone (a pre-existent being which is depicted as the "thought" of God)?
One very important thing to note is that the logos plays no significant role in the rest of the Gospel, where Jesus is "the Son". This, among other things, has led most scholars to conclude that the Prologue is originally independent from the Gospel. Reciprocally, the word huios ("son") does not appear in the Prologue, but a semantically close one, monogenès, "only (son)" (often overtranslated "only-begotten") occurs twice in v. 14-18 (which may be an addition to the original Gnostic hymn). In v. 14 it is interestingly used in a secondary, comparative way: "And the Word became flesh and lived among us, and we have seen his glory, the glory as of a father's only son (hôs monogenous para patros)." V. 18 is quite difficult textually and exegetically, but it might be construed as a complex metaphor: "No one has ever seen God. It is 'God the only son who is in the bosom of the father' (monogenès theos ho ôn eis ton kolpon tou patros) who has made him known." I think this reflects the logical difficulty (in that case for the redactor adaptating the original hymn) of putting logos and "Son" at the same epistemological level. Once the logos is the subject, the altogether different idea of "son" naturally takes a somewhat secondary place -- which is not the case in the rest of the Gospel, where Jesus is the Son.
Which leaves the question open: in the Prologue, is the logos personal or impersonal? Mr. Word or the Word-thought of God? If we look to the Gnostic use of myth, where abstract qualities such as logos, nous or sophia are depicted as personal emanations from the unnamed origin, we might have a clue as to why this is objectively impossible to decide. The text is deliberately ambiguous. The religious (or superstitious) reader sees "someone" where the philosophical (or Gnostic) mind understands "something".