I have used the one sold by Dillion. If one of the fragile spring steel rods on the head gets bent your collected brass will empty out. Other than that, nice idea saves time and an aching back.
In the video that link leads to, it looks like that woman spent 30 seconds picking up what appear to be about ten or fifteen pieces of brass in the cage. Many of the pieces she rolls it over get left behind. It's probably too Mil-Spec.