I replaced our 30+ year old bathroom fan with the SIG80-110MH and am really pleased with it so far. I installed the fan myself which took about 3 hours. This fan was a couple inches bigger than our old one so I needed to cut a larger square in our ceiling. I did have attic access which made the job somewhat easier.The nice thing about this fan is the flexibility. You are able to select 80 CFM or 110 CFM depending on the size of your room. Our bathroom is on the smaller side so I have the full speed setting set to 80. When it is running at full speed you can definitely hear it but it is really quiet and smooth. Of course I did replace a 33 year old fan that sounded like a small airplane taking off so my judgement could be a little skewed.One of the main reasons I purchased this model was for the motion and humidity sensing. I have installed the fan in the bathroom that my sons use and they never turn the fan on regardless of how smelly or foggy the room gets. This “smart” fan turns itself on to full speed whenever it detects movement or the humidity gets too high. After I installed the SIG80-110MH I noticed that the motion sensor does have a very wide line of sight so the fan would turn on to full speed even before you entered the room. This was more than I needed so I put a small piece of tape over half of the sensor. Now the fan only turns on when it detects motion around the toilet or tub/shower. This is working so well that I may eventually remove the wall switch so that the fan can’t be manually turned off.I also really like the fact that you can set the always-on (as long as the wall switch is on) speed. I initially had this set to 30 which is the slowest speed. At that setting the sound is barely perceptible. Due to the extreme cold temperatures right now I have changed the setting to 0 so the fan only runs when it detects motion or humidity. I will definitely be turning it back to 30 when the weather gets warmer.All in all it is a really great product! I will definitely buy another one when we remodel our master bathroom.This is a well engineered fan - a really good product. (My second Delta exhaust fan). They thought through the installation procedure for retrofitting this into an existing house. They designed it so you don’t have to get into the attic or rig it into place.There is one catch, though - it calls for 4 separate switches which is not very practical for a retrofit. The switches are for: the light, the blower, a night light, and a mode selector. The mode selector dictates one of two modes - full power blower with a timer or continuous fan at lower CFM. If you have only 2 switches, use one for the light and one for the blower. Power the mode wire (blue) from the light switch otherwise the timer will not work. They don’t tell you this in the instructions or on the help line. I’m unable to operate the low CFM mode or the night light, but it sure beats wiring more switches into the house.The blower can be really quiet, but if your duct is restricted the noise will be higher. My duct narrows to about 3” dia. The blower noise if fine - tons better than the 15 year old blower that it replaced.Quiet and effective (mine doesn't "chime" - dunno what's up with that as others report; no mention in docs). I have it setup for "always hot" for automatic humidity activation with wall-switch to turn on manually. Can also set whether "always on" from 30-80cfm (or not) and humidity level 50% - 80% (comes on within a few mins of starting shower; haven't compared to another sensor).Does seem to run a bit longer than needed when humidity activated, but since quiet only only draws a few watts, not an issue for me.Not crazy about the blue LED, but small piece of electrical tape is an easy fix.No better/worse installation than any other fan with built-in motor. Northern CA wants rigid ductwork vs flex, which is a bit tight with included 6-4" adapter, but managed. Clear instructions. Satisfied.DC motor starts up and you can hardly hear it in the 110 cfm mode. Mine came DOA (dead on arrival) called them and they shipped a replacement and return label so they could investigate it. Replacement was flawless. There are several versions. This one is the basic 80 or 110 cfm without a light and without a thermister. I have it on a lutron vacancy sensor with the light over the shower. Both turn on when the switch is hit and shut off 15 minutes after the room is vacated. This is my second delta too. The first one I installed over a year ago is working perfectly. You need to be handy and have access to the area above the ceiling. Its not a plug and play.This is installed in a bathroom with no windows, and works very well keeping moisture out. It requires two switches, one is master power, and second to activate the full blast. I tied the second to the light switch, so that when someone uses the bathroom, the fan is running at full speed (110). After they leave the room, the fan keeps running at full speed for another 5 minutes (time is adjustable), then drops to low speed (30 - also adjustable) that runs around the clock. The low speed is not totally silent, you can still hear it when you enter the bathroom, but it keeps the bathroom dry, so avoiding mold and mildew. Very clever product, I hope it lasts.It is so quiet, and so efficient. I have a small bathroom that would always fog up and collect moisture on the walls and ceiling. No more. This was a beast to install but a fun project with a huge value to me. Default mode is 30cfm. Moisture or motion triggers 110cfm for 24 mins. Their instructions weren’t clear on that, but that is definitely how it is. The little sensor led light is perfect for lighting a toilet so you don’t have to blind yourself at 3 am with lights. I would definitely buy delta sonic and this product again.Haven't installed yet but was hoping it looked a little better given the price.Very quiet fan. Good job pulling out humidity.