We have a 8ft x 8ft ReflecMedia pop-up backdrop that folds into a 3ft diameter circle. We love it because:

LED light ring produce even green on the ReflecMedia screen.
No need for additional lighting for the screen.
Talent can be as close to screen as they like. No spill.
screen can be tilted, wrinkled, even wet without affecting the chromakey.

Only complaints are :
Can only be used indoor.
microscopic reflective beads on the screen starts to fall off due to wear and tear.
Cannot be used with mirror-style teleprompter.
Expensive to replace