I really wouldn't do out of phase split on a single humbucker, far too thin a sound. Mad idea IMO. Even two out of phase humbuckers on a guitar have very limited uses. OK for a few Peter Green tracks but pretty useless for anything else. My Hamer with (until a few days ago) two out-of-phase P90 pickups sounded awful in the mid position. Sounds much better with the new bridge pickup and an in-phase mid position.

Series is always going to give a hotter, fatter signal than parallel, but there are times when you don't need that power. A louder sound almost always sounds better to the human ear, but get them at the same level (as when recording and mixing) and you might prefer the sound of the parallel option in many instances.