Who plans to flip over? You don't need to be racing to have that happen. Naturally the chances of this happening during normal driving are pretty slim, but racing does increase the odds.

With that out of the way if you roll and have normal seat belts on the way they are designed you can move down/out of the way. Try leaning to the side with them on and you'll see what I'm talking about. Damn that common sense! With a harness you're not going anywhere. If your car rolls and you don't have something to prevent the roof from collapsing ... bye bye, nice knowing you, see ya later.