This isn't an original idea anyways. You're just trying to bring some PC Era things into iEra, which probably won't happen for a few reasons.
1. people would complain, the idea would be overthrown anyways.
2. hard to implement it to make it just for pk, as body armor in spar would be unfair.
3. making a overpowered gun spammer, such as a PBP user that does 20 damage, have an extra twenty hit points is a bit unfair versus a, for instace, m4 user.