[Pseudonym]

It does include one technique, and neither DFRPG nor GURPS Lite explains the mechanics of techniques, so for a complete neophyte or solely DFRPG user, it might not be obvious that the technique can simply be turned into a five point "power-up."

It makes several references to enchantment, as in, "what enchantments are valid for a piece of equipment with these unusual properties?" which might be slightly different between GURPS Magic and DF Spells and DF Magic Items, but I think they are mostly similar, and that most of the enchantments, if not all are covered by DFRPG.

It has several "perks" and it might not be obvious in DFRPG that they are simply one point advantages (and sometimes have a few special rules in GURPS to limit players to buying them; such limits don't seem to exist in DFRPG)

It also mentions tech level, but that is a mechanic mentioned in GURPS Lite on p.18, so the meaning of the numbers is freely available, and the intro to the pdf explains the superscience caret.

Finally, and very optionally, it has some rules for extrapolating more gigantic weapons that builds on Low Tech Companion 2.

If someone with DFRPG reads "perk" as one point advantage, and the one technique as "5 point advantage that requires specialization (or 6 points really if you follow the pattern in DF11,)" then it's 99.9999% usable.