Product review (5 stars): Surprisingly it works.
Surprisingly the thing works.  It took a bit to figure out how to connect it in the most efficient manner to the dryer ducting and also to get the pressure switch adjusted for the best spot, but other than that it works.  Perhaps the hardest part was getting up in the attic taking the ducting apart and cleaning the duct out.  I purchased:
Deflecto Aluminum Duct with Connectors, Semi Ridgid, Flexible , 4" x 2', Silver (AM42)  (it's cheaply made but for $6 it's worth it for the connection from the device to the ducting)
2 of BUILDERS BEST 111718 Elbow Kit, 4-inch by 8-foot, Silver  (and this from the dryer to the device)
iPower 4 Inch Key Hose Vent Clamp for Ducting Connection, 5 PCS  (and these just because I never have the right tool to clamp them down)

I have noticed that drying times have been shorter.  How much, though I cannot give a definitive answer to as often times we load the dryer up.  I would say for certainty >10 min shorter.

I would suggest using metal duct tape at the seams connecting to and from the device.  I contacted the mfg on the pressure switch connection as the instructions were contradictory on which slot the tubing goes into.  The diagram shows the side furthest from the device whereas the instructions say "NOT the side marked LOW".  It is the side NOT marked LOW.

Overall it works for our application.