3 servo CCPM is easier to set up, and has virtually no chance of the swashplate binding in extreme manouvers. 4 servo CCPM requires more persise set up and works well for scale flying but has a chance of binding up under extreme 3d manouvers.

For pod and boom and sport scale fuselages the 90* 3 servo set up is all we fly. For scale fuselages that cost more money and have hours of building time invested in them the 4 servo set up is highly recomended.