I plan on buying a TechNiche evaporative cooling vest for use in hot, dry climates. I have already made the decision on TechNiche and evaporative cooling versus phase change but need help making two choices and would appreciate comments. First, on a basic vest versus vest with zip-on zip-off sleeves. I just noticed the removable sleeve option on their website. Seems to me the more body area you cool the better. Second, they offer a choice of a typical open v-neck or a high collar. TechNiche states the "high collar w/hook & loop neck closure for additional cooling relief and sun protection, handy front pockets, and zipper closure; designed especially for bikers". This is the first I have seen of the high collar design. Any experience out there with the different sleeve and collar designs?