"Only" 50,000 miles? That would last me 25 years, that sounds great.
I haven't tried a Sturmey drum. They're rare in the US. It cannot be worse than the brake it's replacing, the stock '70s Schwinn sidepull caliper with a warped brake bolt which has never worked well.
Two weeks ago a driver right-hooked me. Everyone's fine, it wasn't a hard hit. With better brakes I might have missed them entirely.
The shop recommended a 700 size (ISO 622) wheel build instead of the Schwinn oddball 27" (ISO 630) size. A 700 wheel would bolt right up to any number of lighter bikes. Rim brakes are dead to me, so most new bikes are too. With a drum brake that bolts right up, all those bikes become an option.
I'll get the dynamo hub version for sure. There's no point in building a wheel without one.