I used to think the same way as you. However, you may want to give some IIIAs a look. THey are a lot lighter and more flexible than they were just a a couple years ago. I was really impressed. You can save a lot on bulk and weight going to a II(A). However, most of us complain most of the heat from wearing the vests. I'd be the first to say I am in this category. However, at a recent meeting with a vest distributor in my area I was confronted with a WAY too obvious fact that I had neglected to see in all these years. DO YOU REALLY THINK THAT A LEVEL II VEST IS GOING TO BREATHE (KEEP YOU COOLER) THAN A LEVEL IIIA??? It's funny when you think abou tit. None of them breath. ALl cover about the same areas and will be just as hot, whether it is .3" thick or .7" thick.
After that I decided to stick with my IIIA. 
Some days I still toss around the idea of getting a II to wear around all the time and then sliding a III over it in a tactical carrier for the hotter interviews/hits... but it hardly seems worth it.
Just a little food for thought.
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."In theory, there is no difference between theory and practice. But,
in practice, there is."
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