I know this has been mentioned a few times, just curious if any of you that have installed these have any updates. I have a split level home, tuck under garage, attic access in the main hall upstairs where I would probably mount a fan. Questions for you: 1) Which make and model is best and why? 2) Is the big difference in price mostly quiet related? 3) My one kid has hay fever pretty bad, although we do open up when we can. Wonder if a fan would make things worse? Thanks gang.