This unit replaced a 24 year old low end rear-venting unit with poor CFM. It was packaged well for shipment, and arrived undamaged with all parts needed for top or rear mounting. My primary frustrations were:1) The old unit 3-1/4"x10" vent was 1/4" down from the top of the unit, and this Hauslane vent was 3/4" down, so I had to enlarge the existing ductwork (not the fault of Hauslane)2) The rear knockout for power was in a different location, so I had to do some rework to move the cable (also not the fault of Hauslane)3) To access the power, you have to remove the bottom cover of the Hauslane hood. There is quite a bit of springiness in the panel, making it difficult to reinstall the 5 screws, particularly the 3 on the back of the unit.4) It would have been nice to have a gasket for the rear vent to provide a better seal to the wall opening.5) The wiring box is tiny and cramped, making it a pain to tie wall AC connections to range hood wiring while crouching under the unit and craning my neck up. This box could easily have been bigger, there was plenty of spare room.Other comments:It took 4 hours to move the stove & clean up the dust bunnies, remove the old range hood, rework the duct and move the power (described above), an install the unit. I had a couple of helpers hold the unit and help guide it into position.There is very little difference in the low/medium/high blower noise; maybe a bit of increase between medium and high. The pitch of the blowers is lower than…