The problem that I can see with the wrap is that if you wrap it from the top down it will allow moisture ingress when riding in the rain, washing your bike, etc.
It's a bit like a weatherboard house, they fix the boards on the frame so that water runs off it, not into it. KC's method works like the weatherboard house theory.
Someone else posted on another thread that wrapped headers will rust out very quickly, due to water trapped in "Dams" created by bridging two pipes with the tape when you get close to the collector. Not a problem I guess on 4 individual headers, but not so good on 4 into 1's etc. Cheers, Terry.