In my experience, the tap splices tend to cut strands of the wire, causing problems down the road with arcing, corrosion, etc.
Take the time and do it 'right', strip, solder, etc., then heat shrink or good quality electrical tape. If you live somewhere where corrosion is common (coastal or damp areas), it helps to coat the wires with grease (regular chassis grease or vaseline work fine) before the heat shrink or tape.
