Product review (5 stars): It works!
I bought the Linteater and the 12-ft. extention through amazon.com (I got them separately rather than together as they qualify for Amazon Prime if ordered separately, and cost was comparable versus together).  I live on the second floor in a 4-story apartment building, with a vent going to the roof.

I do not have roof access, and I don't own a shop-vac, so I wasn't expecting too much.  I figured if I didn't get the brush stuck in the vent, this would be a success!

Well, not only did the brush not get stuck, but I managed to get 1/3 of a small shopping bag of lint out of the duct (that is my weird "trophy" until trash day - haha)!  I ran the brush on a cordless drill, going "up and down" to have gravity help get the lint to fall out.  I made sure always to run the drill clockwise, and never on "full blast" (it's a variable-speed drill) until the battery started to go (then can blast away)!  I was going to use duct tape and pliers as recommended to hold the pieces together, but they seemed solid and I was right - the spinning motion of the drill (again clockwise) kept the pieces from coming apart.

And here's the bottom line - besides reducing the risk of fire, my drying time went down from 83 minutes to 59 minutes.  Maybe this isn't as dramatic as others, but again, considering the conditions I have it's not bad (a roughly 30% reduction in drying time)!  I'm very happy with these results and would recommend the Linteater to anyone who has a dryer!!