The less 'spaghettilike' parts in your oil (for viscosity, sorry can't think of the name) the better, as they get cut by our gearboxes. So in the end you'll always end up with a somewhat thinner oil. I remember Yamaha also prescribed 20-40 for some models. Long time ago, when I had my first (summertime) job as a teenager at a garage, you had two types of multigrade oils: 10W-30 for winter, 20-40 for summer. In those days people used to change oils twice a year. Than, if my memory serves me well, Esso was the first to come with an all season 10W-40: Uniflo which was an excellent oil that hardly left disposits (lacquer) and kept your engine remarkebly clean. IMO viscosity 50 is for extreme heat, like crossing Death Valley or Andalusia in summer. Important is that every coldstart oil reaches the topend within 8-10 seconds maximum. If wear takes place in our types of engine, it's most likely at the topend, the bottom end lives forever. BTW, that's why the topend of the CB350F is superior to the other Fours.
So, to conclude, oil will always be somewhat a compromise. Pick the one you like best, that is: offers the best for your climate and your use of the bike. I don't do short rides. For less than 12km I prefer the pedal bike. Better for my bike, better for me, better for the city and better for the planet.