The Riff Raff is certainly on the brighter end of humbucker voicings, so it'll definitely work just fine in the neck position. Dynamically, the bridge will perform much like the proper neck version, as they share identical architecture and magnet setup - the bridge just has a slightly hotter wind which will fill out the lows a little and produce a touch more output, but certainly well within the realm of a great neck pickup when paired with a hotter bridge.
