Alen 45i has important features. Being able to see what the quality of your air is, is so helpful. When I find the quality lower than I would like, I turn on the top speed. But when I see the blue quality light I click to auto and that is where it stays most of the time. In time I will be able to better judge any weaknesses the 45i has but at this point I can only say I like the design and the coverage seems good.