Four Wheel Alignment

String method

We still use the old fashioned front wheel alignment laser track gauges at our place. which are okay most of the time until proper misalignment becomes a headache. 

I have seen a four wheel string alignment system by BG Racing where they have a frame that positions against the front bumper and one that positions against the rear bumper. You remove all the road wheels and connect four plates to the wheel hubs directly that sit on the ramp platform. By adjusting the front and rear horizontal bars you then put strings along the side of the vehicle front to rear. The accuracy is assured by ensuring that you position the horizontal bars in the same position front and rear. The bars are calibrated for this. When the strings are connected to the bars you simply measure the distance from the centre hub caps to the string to ensure that each horizontal bar is positioned correctly. Now you measure the linear distance from the front and rear of each wheel the same as you would with track gauges. I'm to understand it becomes clear very quickly which wheel toe it out of adjustment. 

Anyone use this method and if so what do you think about the accuracy of it?