I would not rate this hike as moderate - it is definitely difficult!!! The climb up Olallie Ridge from the Castle Rock trailhead on the west end of the ridge is a particularly tough 3,000 ft slog. But once you're on top, its fairly level with some nice views of Sawtooth Ridge just to the South. If you scramble up MacDuff Mountain, there is a nice view of the McKenzie River Valley as well as a plaque that was hauled up and installed by an early hiking club. When I did this in 2015, USFS crews were improving this into a Mtn Bike trail so it should be in fairly good shape. My understanding is that bikers ride it East to West to avoid the bad climb.