A lot of people questioned him about that on his Youtube page. Apparently the main difference between the the 3 models is the Ariens snowblower has a faster impeller speed and longer chute but all 3 have around the same power. I'm not an expert on this so I can't verify whether thats true or not.
We will have to see how mine works when we get some snow. I just got it over the summer and have not used it yet. It has a 13 HP engine and sure moves a lot of air sitting there in the garage with the augers going.