ok i understand you dont need defense for s ships, but at what point does it become counterproductive.
  how about some answers to noob questions

 should mid size say 500k to 100 mil have some 

are mission fleets determined by the size of your largest ship? 
i made a 12bil ship got my a## handed to me my other ships were way smaller..

when adding shields is there ever a reason to have more than 6 shield sets am i missing something?
seems that anything beyond that doesnt add significant abs for the cost.

is the comp stack formula the same as the shield stack formula

thanks
ken