The brake option will not slow the plane faster with the prop being stationary vs free spinning. There was a discussion on another thread regarding this by a real pilot. Kinda threw me off as well... but figure since the person was a real life pilot they know what they're talking about.
With the stryker, when using longer props, the brake helps you get the prop to stay put for landings. If I glide past and see the prop is hanging down, I'll blip the throttle to try to get it horizontal before touch down. I drug a prop once on frozen grass... ended up transferring the stress to my motor mount and cracked it. Those APC-E props are rigid.