I am also a big coaster brake fan. My bike can approach 50mph on an extended stretch, so I obviously do not depend on the back brake for quick stopping. Up front, I use a Honda C100 front drum brake. It’s not as large as a full size motorcycle drum brake, but it stops me really well.
I use the Morrow coaster brake mentioned in this thread, it is from another era, built crazy strong, large bearings, very large shoes. A friend of mine told me about the Morrow brake, they were used by the original “klunker” mountain bikers in their downhill races in the ‘70’s. When I race, I put a lot of stress on the brake, and the grease gets hot and flings out of the dust cap. By the end of the day, the bearings need to be repacked already. For daily riding, I usually usually repack the bearings every 2 or 3 months, depending on mileage.
Like everyone else says, if you use a quality vintage hub and keeping it well greased, coaster brakes will not fail at speeds. It just cant be used for the main braking force.