Two poles and fly away self-launching pole systems are legal but more usually seen on Merlin Rockets. Simple single pole system are widely used and crews are familiar with them.

Twinning lines (barber haulers) are IMHO better than the slightly simpler reaching hooks, as they make it easier to gybe and control the spinnaker, particularly as the wind increases.

The ‘balls’ system limits how far the guy will go out, and sets the pole on the forestay. This is useful when gybing, and means that the guy is never fully uncleated and free to run out. This helps prevent capsizes due to failure to cleat the guy, resulting in the spinnaker moving round to the side and dragging the boat over :roll:. However many boats do not use the ‘balls’ system, perhaps because it is slower to (leeward) hoist the kite, as there is not enough slack to fit the pole and pull down the twinning line, before the hoist/windward mark.

Halyard pump systems are very difficult to make work reliably. Further recommendations for racing would be to use tapered spinnaker sheets, rig the sheets to minimise friction by having only two turning blocks (eg in the sidedeck and at the thwart), and fitting autoratchet blocks.