Well, yesterday I rode a ride that has shoulder bars where the shoulder bar is so poorly designed that I could barely get the safety belt to latch because the pivot point is too low. And it's a good thing the safety belt is there, because had I slid forward a little on the seat, I could drop right out from under the bar. Pathetic.
Personally, I think shoulder bars are contraindicated on almost all rides. If a ride is gonna hang me upside down, I'd much prefer a lap bar to a shoulder bar. Take a ride on a Ring of Fire and a Kamikaze and see which one is a more comfortable way to hang upside down.
Anyway, when a secure restraint is called for, as when hanging upside down, I rather like the Eyerly belt-bar. Otherwise, keep it simple. And if the ride feels like it is going to throw you down the midway...well, it's an amusement ride...it's SUPPOSED to be a little frightening. So long as it *doesn't* send you sailing down the lot, of course. Ride ops have enough to do without having to chase down their patrons to get those extra tickets...
--Dave Althoff, Jr.