We set up the 75i on September 13, 2020. The air sensor was blue right away, which is the best air quality, and I thought this was odd. We have two 85lb. dogs. The only time the color goes to red or orange is when I am cooking bacon or other things on the gas stove top, We ordered the 75i due to our open concept first floor and cathedral ceilings in our family room. It is very quiet, but honestly I've not noticed any difference in dust levels or allergy issues. The wheels are nice. It is easy to set up and the display panel is easy to use. I like how you can turn off the lights on the display panel. The warranty is very good if you subscribe to the filter replacement plan. All factors considered, for the cost, I'm not sure we will be keeping this unit but want to give it a bit more operation time. We do have it on 24 /7. We also have the Breathe FLEX in our bedroom, again making our choice based on square footage. I will post a separate review for the FLEX model.