I totally agree with you on the subject of heat and velocity and can cause great variation.We got about a 6deg drop in temps when thermo wrap was used.Mind you this was placed on top of the HPC downpipe.Still it probably works as its used in lots of race applications but I think as a personal choice I will go with thermo wrap from now on.
Anhar Khamas GT4 Group A
If thermo wrap = header wrap, I'd advise against wrapping your headers in it. I have heard from a few people that they have cracked/damaged headers from wrapping them. It doesn't let the heat out into the engine bay, but it does supercook your headers. Much better to get them coated I think. You can get the inside and/or outside coated.
I guess having the inside done would stop the header getting as hot in the 1st place.