They shortened the P measurment to improve the IOR rating. To do this they had to make the J measurment 1' longer to keep the center of effort of the sailplan in the correct location. Making the rig taller added ~6' of luff length which helped upwind performance. This tall rig with short boom was also meant to fly a blooper while sailing downwind to make up for the loss of sail area on the smaller main.
How is the in-cockpit sheeting arrangement on the older 41? Seems like it would be great for single-handing; but difficult to deal with on downwind legs and gybes because the mainsheet would drape across the inner cockpit.