One point I have used is using an unsupported barrel causes the leads to be clinched per 5.2.7.2 which costs more with the added labor. The main reason I have found that customers choose unsupported barrels is to save a few bucks on the PCB. The added labor reasoning normally gets most customers to see the cost savings is really in using a supported barrel plus the added bonus of the mechanical strength the barrel does give. Kathy