well...... i bought a progressive and thought it was excellent, but now ive got a cocker and i use a freak system as i play tournies and we use lots of different size paint
bore systems are good , but are more expensive,
i wouldnt advise a bore system kit for this reason, they are expensive, and you are likely to buy another marker soon which wont have a spyder thread, so u will have to fork out another £40-£50 for a new freak back