I dont know what you are referring to when you say "Big Outer Reaps", but on the granby question, it depends on the type of roll. Two possibilities are to completely let go and follow the roll, then return to control, or to hold on and ride it out.
I also have no idea what big outer reaps are. How I would defend against the granby is to stop their momentum as they finish the roll. Catch their body. Block their hips. Elevate your body so they finish under you. I would just say you have to react fast regardless of what you do. Here's a video of my failed granby attempt. See if you can pick up on what the other guy did. Or maybe it's just what I did wrong. Either way it's 1:06 into the video.
Large outer reap is the english translation of the Judo throw O Soto Gari.
I am not familar with a wrestling variation of this, since it will not work with someone in a wrestling stance.
I also have no idea what big outer reaps are. How I would defend against the granby is to stop their momentum as they finish the roll. Catch their body. Block their hips. Elevate your body so they finish under you. I would just say you have to react fast regardless of what you do. Here's a video of my failed granby attempt. See if you can pick up on what the other guy did. Or maybe it's just what I did wrong. Either way it's 1:06 into the video.