Quick story about possible effectiveness. (I think this indicates the wrap did reduce the heat).
I built a set of 4 into 1's with larger diameter head pipes.
The new head pipe material is very thin walled compared to the stock head pipes.
On initial installation, the heat from the larger head pipes melted the ends of the cooling fan.
(NOTE: The larger head pipes are very close to the fan).
I removed the headers, and wrapped the head pipes. Installed a new fan and tried again.
Fan didn't melt.
Some of the pipes I wrapped have been on the bikes for 10+ years.
I agree that the wires could cause hot spots.
I'll even agree that it could eventually hurt the head pipes.
I personally have not had any failures.
NOTE: I used stainless safety wire.
Bottom line: I don't think there is any performance improve.
I do think it reduces heat slightly.
If you want to give it a try, go for it..
Ride safe, Ted
PS: I've removed the home made 4 into 1's and their hanging in the shop.
Can look them over for damage if anyone's interested.