When we moved into our house, the screen on the back door had some holes in it, so I knew that I wanted to replace it. I decided to purchase the flexible screen kit. I was thinking that this would help keep the screen from popping out and the screen door on the track, when the kids started pushing on it.
The screen never did get popped out of the door, but the door seemed pretty unstable, and was falling off the track. Also the screen was pretty dark, so it was hard to seen in and out through the screen. After about 3 years of use, some holes started to appear, I decided to just go to Home Depot and pick up a standard screen.
After I installed it, I noticed that the door itself seems more stable. I think that since the screen is less flexible, the door has a little more structure. Also, there is more visibility looking through the screen because it is a lighter color. As for the screen popping out, we are just making sure that our son doesn't push on the screen. (Unfortunately, he got used to being able to push on it and it having a lot of flex.)