The 13 handles better than the 8. I was worried that the fat rear tire would impact the handling adversely, but that certainly isn't the fact. The difference isn't large, but it is noticeable.
The 13 has more power. I didn't expect this since they both have about the same horsepower. I guess the difference comes mainly from the lower geared sprocket.
The ride of the 13 is harsher than the 8. Again, not by much, but I can fell the bumps more in the 13 than I did on the 8.
The change in the fairing angle is very noticeable when comparing windshield lengths. My 8 windshield, which I mounted on the 13, was 2" taller than stock. But, because of the fairing angle, it sits another 2" higher when mounted. Setting the windshields side by side, the 8 is about 5" longer than the 13.
The 8 seat is better. This is a HD aftermarket tall boy seat. The 13 stock seat is definitely better than the 8 stock seat.
The exhaust on the 13 is louder than my stock 8 exhaust.
Although the weather was cool (50F), I expected to feel more heat from the 13 than I did with the 8 when soft lowers were attached. But, I didn't. The 8 had IED's which cooled if from stock while the 13 is stock. A pleasant surprise.
The buffeting on the 13 is MUCH worse than it was on the 8 even with a taller windshield on the 13. The dealer had neglected to install the wind deflectors. I am hoping these will make up the difference.
Not near the gear whine on the 13 that I had on the 8. Either that or the 8 compensator was a lot more worn than I thought.
All of the differences are slight, but noticeable. Overall I am very pleased with the 13. If the wind deflectors fix the buffeting, I will be very happy indeed.