The top down bottom up feature is a great way to add versatility to shades. The one knock on standard shades (bottom up) is that they go two ways, up and down. So your treatment is either opened or closed, there isn't much middle ground. The top down bottom up adds another rail in the shade that can be lowered from the top. Now you have to moving rails in the window, the bottom rail and a top rail, thus making your shade do a lot more.
It's a nice feature on any shade but it seems to make the most sense on blackout shades in the bedrooms. It's 6:30 in the morning, I'd rather not turn on the lights, I'd rather not have to raise my blind up sacrificing privacy, it just makes sense to drop the top a few inches to let the early sunlight in. It doesn't have to be added to every shade, I'd reccomend using it on either the biggest shade in the room or the shade that you use the most.
Although plantation shutters have little in common with shades, they can utilize the top down bottom up feature as well. It's called a split tilt. In the privacy rooms, bedrooms and bathrooms, I reccomend people split the louvers at around head height. Now you have two seperate channels for your louvers, you can close the bottom 2/3's for privacy but leave the top few louvers opened to allow light in. Making your treatments as versitale as possible without making them complicated is a win win.
AAA Blind Factory
28200 Old US 41, Unit 207
Bonita Springs, Florida 34135
My Experience with AAA was Exceptional