Carbs and reliability
Well, my very small sample, from which one may or may not generalize is this: R75/5 carbs: (35 years, 180,000 miles) one choke gasket, replaced with homemade item, replaced floats with alcohol-proof set; replace diaphragms every ten years or so.
R90/6: 60,000 miles, 30 years (time off for young kids): Diaphragms only.
R69S: Only about 20,000 miles: Rebuilt carbs once in 30 years.
R50: Only about 10,000 miles. Rebuilt carbs once in 30 years. .
Honda 350 #1: About 8000 miles. Pinholes in float from corrosion, fixed on road and replaced later.
Honda 350 #2: About 25,000 miles. No carb issues at all.
Harley Aermacchi 250 SprintH: 17,000 miles. (yowza!) No carb attention. (but lots of other attention).
Carburetor breakdowns that left me stranded: Zero.
It's hard to improve on zero.
Don't ask me about aftermarket electronic ignitions, though. 4 strandings there.
Interestingly, I think I have had more car carburetor trouble than motorcycle carburetor trouble, even though I probably have more miles on bike carbs than on car carbs. Zero trouble with car FI, though.