Product review (5 stars): Seems to work great.
I monitor my electrical usage closely.  The efficient fan option of this is why I got it. As well as some savings for heating and cooling modes.  It effecient fan mode works great for my corn/pellet stove hot water exchanger in the furnace plenum.  Also install was fairly simply. Had a little fight with the belly band to get the holes to line up, but it wasn't bad. Belly band sold seperately btw.  I did a temp differential test. The speed setting for this motor match the speed settings that I used on the old fan motor.  I recommend this. Huge money saver if you run your furnace fan 24/7  or frequently.