Depends whether you want to reduce the under bonnet heat or not.
There is some evidence that wrapping a stainless exhaust can reduce its lifespan, but only by a few years. Bearing in mind that they can last for decades a few years won't matter.
Opinions are divided and evidence somewhat unreliable. I have heard that wrapping can increase the chances of welds cracking on SS pipes and increasing the rate of rusting of mild steel pipes. However, on a new mild steel system you will have sold the car or rebuilt the engine long before the pipes rust through. Likewise with SS.
A good system should not have problems, but wrapping will find any weaknesses in an old or poorly made header.
Wrapping will allow the gases to exit quicker as it keeps the heat in and speeds up the process. However, you risk the manifold cracking due to the extra pressure.
You have to look where your manifolds are.... are they near anything that won't like excessive heat? if that answer is yes then wrapping is for you, bonnet vents are also good for reduceing under bonnet heat.