definately get one, other than theyre illegal theres no probs with em.
advantages, all the oil blow by vapour doesnt get recycled back into you engine. normally this blow by ends up coating the inlet piping with oil, the vapour also effectively lowers the octane rating of the fuel making the motor prone to detonation
Can get a jap one for around 2-300 or get a custom one like i did for alot less