Hi,
I'd say Wez is right, not every pick-up sounds good coil split.
Without stating the obvious they can often sound lacking as they arent a normal 'power' single coil pickup when split.
They can sound like a split coil as opposed to a normal single coil if you see what i mean.
My attitude is always to aim high though, see what you get, maybe you'll love the in/out series parallel switches, but try and fit it so that you can go back to how it was originally, i.e avoid drilling holes if possible.
The most noticable differences i find are bass variable response, and often times it seems to take the character of the instrument away slightly in the new positions.
Who knows though, if you can find a great new tone its well worth it!
cheers,
steve