Got both the Cool Rails and the Little '59, both neck versions, in two very different superStrats, both with series/parallel wiring for the neck pickup.
The former is in an alder body, bolt-on maple neck with a rosewood fretboard Jackson DK2. The Cool Rail in series sounds indeed very balanced, and it shows its versatility in the way it handles both high gain and clean tones. Parallel has lower output, slightly changing the EQ to a more trebley but yet puncht tone, perfectly suited for Fender-like tones when using clean.
The latter is a mahogany body, neck-through maple neck with an ebony fretboard ESP LTD MH-1000HS. The Little '59 in series sounds fuller in the mids and has more output than the Cool Rails, but that has more to do with the guitar woods and construction. Definitely sounds more vintage than the Cool Rails, and I prefer to use it with gain than with clean tones. Parallel cuts output, bass and middle more evidently than the Cool Rails, and makes it more usable in clean tones. Yet, to get LP-like tones from a Strat, this is the one to get.
This guitar came stock with a Hot Rails neck, but it just had too much gain and mids to my liking. Definitely a Dave Murray from Iron Maiden tone, but while I love the band, I really didn't like the pickup voicing.