Well done, gentlemen. Curious how long before some rain brings it all back.
Good question. It appears that, over the years since Easy O was first climbed, erosion has averaged roughly 1/3 inch per year on average (about two feet, as I remember it appearing, in 71 years). Of course, even if the average rate is correct, the rate for any one season could vary (and has varied) very considerably, both because of the frequency of human traffic and the severity of weather.
If 1/3 of an inch is in the ball park, the area isn't going to look like the "before" shot for several years, and our guess that the cleanup will last a season seems pretty reasonable.
Rick's comment about water bars is on target. At this point, the top is a water chute that will continue eroding whether or not anyone tops out. But the lay of the land will make the water bars drain over Easy O, which could create new issues. I think it would be well worth having folks who know something about trail-building assess the drainage situation and see if water bars are a good idea; they certainly are called for in terms of the erosion of the present terrain.
One of the things that became apparent is the debris from the top does wash over onto the ledges below. We did try to clean up the ledge immediately below the lip, but, having brought up only a short static rope, we couldn't rap further to clean ledges lower down. The fact that debris from the top does end up on lower ledges makes the top clean up a good thing even if people aren't going to top out.