Originally Posted by Radiation Joe
Care to elaborate?
I've heard this argument before, and I don't buy it. The quick fit (or is it rallye?) fastens to the seat belt anchor at shoulder height in the rear. The old argument that you can compress your spine in an accident doesn't apply. There was a valid argument about not using a harness bar due to roll-over concerns (the seat might not collapse in a roll-over). Without a harness bar, I don't see how a 4-point harness isn't better than a three point belt.
There will always be "what-if" arguments regarding safety equipment. You might as well say you won't ride in a car without 4, 5, 6 point belts because you can't support your Hans device. 4 point belts (properly installed and utilized) are safer than 3 point belts in the vast majority of situations.
With or without a harness bar if you put a car on its lid the roof will colapse. If you do not have the mobility to move as the roof colapses then your head and neck will take the brunt of it. When you flip a car with a normal 3 point the shoulder harness slackens allowing you to be pushed towards the floor of the car (now the roof). To my understanding the Rallye replicated the tightening affect of impact that a 3 point does, but not the ability to release upon roll.