Longer rudders make up for the somewhat skimpy centerboards preventing lateral drift, providing lift, and better control going downwind with speed, especially with the MX sailplan. I decided that I ever wanted to sail with spin I would sell the P19 and buy a boat that was designed for one. I was perfectly happy sailing the original rig, original rudders for 12 years. If you would like more power, more speed, etc. then you might prefer the upgrades. The new jib comes all the way down to the level of the bridle tangs. That leaves no room for the spinnaker pole. I suspect you have read Harry's posts on the subject.