I figured I'd do a proper comparison with the balls today, because yesterday I literally just took 10 swings with the 3-piece and then 10 with the 4-piece, no warming up or anything. So naturally, I should have expected to be further with the 4-piece ball after getting loosened up. Today, I hit about 20-30 balls to warm up, then did 5 with the 3-piece, 5 with the 4-piece, another 5 with the 3-piece, and another 5 with the 4-piece. I then picked the 5 best shots with each to compare, and I noticed a few definite patterns.
-I was still longer with the 4pc, not as much as yesterday but still a good 9yds longer carry and 12yds avg longer overall, which is a full club distance.
-Even though my swing speed was a tad higher with a lot of my swings with the 3pc ball, my ball speeds were quite a bit higher with the 4-piece. For example, when swinging 78mph with the 3pc the ball speed was 92mph, and 78mph with the 4pc produced a 98mph ball speed. This no doubt is contributing to the additional distance.
-The launch angle was virtually identical with both - I averaged 24.9 with one and 25.1 with the other. But I got a lot more spin with the 3pm ball, averaging almost 7,900rpm vs 6,500rpm. I think the additional spin combine with my already-high launch killed the distance a bit as well.
-I was more accurate with the 4pc ball with a 6yd dispersion from right to left, while the 3pc was 14yds. In addition to the higher backspin, I also had a lot more sidespin which is what caused the ball to veer offline more easily.
So for me, the original 4pc ball is definitely the clear winner across the board! But I'm a fairly hard swinger with a naturally high ball flight and no problem generating spin, but a slower swinger who needs more spin they may like the 3pc ball better.
In these charts, the first 8-iron is the 3pc ball and 8-iron #2 is the original 4pc.