So my armor worries are lessened but not gone, i'll wait for beta to start bitching again.
Unlike previous versions of Body Armor in Bad Company, this Field Upgrade in Battlefield 4 is more similar to the more limited setups in BF2 and BF2142. It does not increase your overall health, instead it makes the small upper chest hit box more resilient to damage, equal to the rest of the body. In practice, this means that snipers can’t 1HK your upper chest at point blank ranges. It also provides some small protection from shotgun burst damage, though your head, legs, arms, and stomach remain unprotected. At medium and longer ranges, the armor has no effect on how many bullets it takes to kill a player. Essentially, Body Armor is for countering CQB sniper rifles, and not much else.
More info in the link: