An advanced medkit is a good idea, but I don't think it should be 12 TU to use. That would make it too powerful, I think. If the advanced version was a little more effective, that would probably be good, but keep the TUs high enough to restrict 2x use/turn to specialised medics (no armour, pistol, medkit, => 40+ TUs). At 12 TUs, more experienced troopers could actually get 3x uses/turn, even geared up.