when flying your adv train or whale or any kind of slow moving or heavy ship. i think that cockpit view is the only reasonable way to fly it.
when trading you just know when to hit the F3 button to either fastdock or dock to tradelanes and JH/JGs. also you can really easily dodge asteroids when you're flying through said field.
i couldn't imagine anymore how painful it would be to fly a transport without the cockpit view:D
When using standard-loadout (guns) ships, i use cockpit view. Reduces my usual fps issues, as it doesn't have to render a whole close-up view of my own ship.
When using missile-loadout gunboat(s), i use external chase view. It gives you a slightly bigger angle of vision, specially while turning, so you can fire the missiles at more extreme angles (basically, when turning you can fire at a fighter who is right on your side, and to some extent, fire backwards)