Informed by a route description on summitpost by TacoDelRio (man, that dude is everywhere!), I experienced the Sugarloaf Ridge route on Ontario Peak on Saturday. Here is the trip report: Crazy for the Grovel
Your descriptions of the ascent and descent routes of the scree slope are dead on. The ascent route with stable rocks had quite a few ducks marking the route when I went up back in July.