splitting- using only one coil of a humbucker (making it into a single coil essentially)
tapping- using only a portion of the coil of a pickup, lowering the output
push pull pots- knobs that contain switches, utilized by pulling/pushing knob. The advantage is not having to drill another hole for a switch in your guitar
I consider all of the above advantages

Its good to have options
DDs sound great split, just like a strat pickup but hotter

look for diagrams on the SD website to do it
What guitar are they going in?
slade