shadowlord-
I was thinking 1,2,3...light, medium, and heavy. And if you had feats/proficiency in them then 1,3,4. Only 'cause I don't think light should give too much. Although 4 for heavy is pretty nice, it is some big armor, being ceramic plated, kevlar and all sortsa goodies.
I definetely like this idea, because in movies bullet proof vest don't help people from getting hit, they stop them from dying. And so your defintely on to something. Obviously you could argue that if the attacker hit the character and it was because of the AC he got from the armor then the bullet was stopped by the vest and it would look like it does in the movies. *shrugs* I still like your idea of adding to the MD.
Tellerve