You can barely duck behind a tall windshield on a Vs. 650 with NO tank bag: forget wind-drafting advantages of leaning over with any tank bag. Tank bags are not for motorcycling. ymmv
you say some of the strangest things.It's ok for hard-core, do nothing but tour riders, full-time commuters, or Shriners, like you. I just ride all bikes the same way, the way motorcycles were meant to ride on the streets.
:dgi: you must be shorter than me because at 6'3" I can tuck and have my chest resting on the tank bag and my helmet almost hitting the handle bar. it is never in the way. I ride almost every single day on narrow curvy roads and use a tank bag more often than any other cargo option (I've got top bags, saddle bags, backpacks) and the tank bag is the most convenient and least intrusive to the motorcycling experience. the only time I ride differently than how I ride on road is when I ride off road.
or is this more about your slip streaming aerodynamics for top speed runs in half chaps?