Figured after being quiet in this discussion I'd throw my 2 cents in.
Would be a huge fan of the LAW/RiotShield/Medikit shown on the back. I think a backpack/armband is enough for medics. Modern medics don't wear big white helmets afaik. Just a patch and a backpack sign or something. In contrast to ^, I really HATE big white helmets

Definitely think the Geneva Convention should go out the window. Let me kill wounded soldiers

Would love to see more AI with vests and less AI with medikits. Agree 100% with you on that. Same with the XP or RP bonus. Either or. I think in regards to killing wounded enemies, only knifing a wounded enemy loses XP/RP. Otherwise, putting the SOB out of his misery with a bullet should be a neutral act. About converting/healing enemy units. That'd be funny. Almost like the WOLOLOLO of AOE2 hahaha. Not sure how I feel about it. Wouldn't really mind because it only comes up once in a blue moon. However, healing enemy human players to change their faction shouldn't work.
About the way vests work, wouldn't mind seeing more "hitpoints" added by wearing vests. Would make a vested character more bullet spongey which is fine by me. Even a little bit of bullet sponginess makes a huge difference in a game where 1 bullet = death.
While we're on the subject, a couple things i'd like to see relating to medics, classes and things of the sort.
1. Bullet vest model to tell who is and who isn't wearing one. If it's hard to see, a special helmet like a black one could make it easier to tell who has a vest on.
2. Damage model for said bullet vest model so you can tell if you are getting hits on the vest or not.
3. Dragging wounded soldiers to and from cover. Adds a bit of realism and tension to being a medic.
4. Being one of the poor folk without a widescreen, thanks MrNuckFuggets

That's all for now folks.
ComJak