Funny thing, we've had the exact opposite experience.
We spent 3yrs full timing with a standard tailgate. Never came close to hitting it (obviously had to drop it for hitching up) and never had anything sucked out of the bed and we had a couple 5 gal fuel jugs that were empty most of the time just sitting there.
When we got the new (to us) truck last summer, the tailgate had a big dent so Tammy found a V-gate on craigslist for $40. First time using it we clipped it with the pin. Luckily it is plastic and just flexed and popped out of the hinge with no damage.
Then this past summer we have lost boards and a cooler half filled when they got sucked out. I think short of doing an aerodynamic analysis, it's a******shoot.