I first bought my racks as a space saver due to some private catering I was asked to do. I pretty much stick to the 3-2-1 method of cooking ribs. The three hours they spend on the racks I think helps them more than anything. I noticed it prevents the hot spots from turning them to dark. As Arlin said I have also rolled them as well and that worked pretty good too.
I use them as a space saver. Fully loaded they take about 8 hours cooking time and I rotate them around every 1 1/2 hours. Mine will fit 48 slabs in a Lang 84. The most I've cooked was 71, I had rib's everywhere.