Hard to guess what those of you who claim to have wrecked trannies and clutches did wrong downshifting. But I've been doing it since 1960 on sticks and autos and have never wrecked or blown any. If you want to depend on brakes only for steep downgrades have at it. If on an expressway or where they have runaway ramps keep your eye out for where they are. Also get a plan for what are you going to tell passengers about the smell of cooking brakes, the smoke exiting the rear or the "Oh SH%T" moment when you realize your brakes are gone