It's not a question of "out-of-phase or parallel"; rather, it's out-of-phase or in-phase, AND parallel or series... that is, you can be P-IP, or S-IP, or P-OOP, or S-OOP. After having several guitars with countless wiring schemes, I've come to really like the standard P-IP (parallel in-phase).
If you want to go OOP, I agree with Woodman: P-OOP is REALLY too thin for most applications, though it can sound AMAZING thru the right overdrive.
Get some alligator clips and experiment; that's the only way you can be sure to choose the one right for you.
