Product review (5 stars): Installation, a little thought required to do it right...DUCTED
Was going to buy the Broan QS230SS from Amazon, then walked into Lowes on 12/30 and found it at 20% off the list of $319.00, plus had a $30.00 Lowes' coupon in my pocket for over a $150.00 purchase.  My lady liked it for her kitchen, once reading reviews here and elsewhere, so we bought it as our annual New Year's Eve purchase for the house.

This is what I did to replace the existing poor old ducted range hood, begging for retirement. The instructions could be a bit better for the ducted installation.  There are steps that need to be included for duct installation, like removing certain additional pieces in the body of the hood. The yellow information tape at the back and top middle covers up the rear adapter sheet metal mounting screw.  You find this out after using another screw hole in the adapter and top that is for attaching hard duct (I suppose...).

IF Broan wanted you to easily install this range hood THEY COULD INCLUDE A MOUNTING TEMPLATE!  But NO...you have to measure everything out.  I did the old child trick of placing graph paper on the corner of the hood, aligning the front and side edges and then rubbing a #2 pencil over the mounting hole/slot locations and the power hole.  This created a template I used to transfer the location to the underneath of the cabinet.  (The old hood mounting and power access did not, of course, match up!)

There were only three (3) mounting screws in the tiny parts bag so that meant another trip to the store to try and match the proprietary Broan provided screws.  The Broan Screw heads are larger, to match the wide mounting slots.  A #10 washer made up for the difference.  This actually worked better as more surface is holding the unit in place. Both front screws were replaced with the new screws and washer combination.  Measure twice and make pilot indentions for the mounting screws AND the location of the power feed hole in the above cabinet (in our case).  A hole saw is a plus here.  Be sure to make the power hole slightly larger than the hole you have opened by removing the metal slug in the hood top or rear (as applicable).  Do use the conduit screw in strain relief fitting to protect the power wires going through the metal body (why the cabinet hole has to be bigger).  As usual, none of this is included with the unit.

A length of 7 inch hard duct is needed to connect the Broan duct adapter to the existing duct, be it hard or accordion style.  If you are replacing a ducted hood you will find the existing duct work coated with grease inside, awaiting the proper conditions for ignition.  It should make for a home destroying fire, so you may consider replacing the existing duct if possible.  Our existing duct is the accordion type, requiring another trip to the store for a piece of hard duct to use as a connector.  While you are at it, get a roll of aluminum (METAL) duct tape.  What is commonly called "duct tape" sucks.  It is messy and will come loose with heat and become brittle in short order.  The metal tape will seal and stay in place.  By the way, be prepared to trim that "Minimum Length" 2 foot piece of hard duct to the length you need  BEFORE snapping it into shape.  FORGET drilling holes in the hard duct and range hood top duct adapter like in the instructions.  When you get the Broan unit in place there is no way to get a screwdriver in position, due to the thickness of the cabinet base and the SHORT length of the adapter flange.  Make sure to cut, or enlarge, the duct opening in the cabinet bottom to allow for variance in fitting the duct.  You can then use the metal tape to seal the connection to the adapter AND the existing duct. (It will stay in place nicely.) Clean surfaces of grease, etc. with rubbing alcohol to allow the metal tape to adhere.  Also use the metal tape to cover two existing holes in the top of the hood body and around the adapter flange mount.  This eliminates exhaust leaks into the body of the unit and the "smoke coming out the lights" one reviewer mentioned.

Once installed the QS230SS performed flawlessly.  All 3 speeds are accessible individually so you do not have to step 1-2-3.  Press the button once to turn on press again to turn off.  Same for the lights.  I cannot imagine people having a problem with this but it seems they do.  Perhaps Broan would be wise to add more information on the operation as well as adding an installation template.  Look forward to a fun day of DIY to get this job done. Have someone to help with putting the hood in position AND...PICK UP EVERYTHING you will need with one trip to the store, now that you know what you REALLY need to install ducted!

This assumes you have the tools and associated skill to use them.  The only "special tool" might be the metal cutting snips.  May your installation go well!