One of the reasons why a cooling vest may be useful is the effect of cold induced thermogenesis on mitochondrial function. I'm sure everyone has watch Dr Wahls Tedex video Minding My Mitochondria.
Whenever you hear people arguing about nutrition and diet the emphasis is always on the energy in must equal energy out equation and people get very stroppy about the first law of thermodynamics (usually forgetting the second) but they totally ignore that fact that it's all to do with HEAT.
The body has a set point for temperature in the same way it has for fat levels.
Regulating our temperature, whether by cold vests or by cold baths, is another way of increasing ENERGY OUT and giving our mitochondria a boost.
There has been a lot of fuss recently on various Paleo/Low Carb forums about cold water thermogenesis. There is a summary of the approach here That may lead you to consider it as a strategy to boost mitochondrial function