Just point on the medic revive perk. I prefer to have the time it takes to charge up to 100%. It gives you the required time to judge whether it is safe to do the charge or not. I may get the odd one wrong but if I do revive you, you will have a chance of getting out or away.
The ones that do the 20% charge are the ones that drive me insane. This is usually because it’s a hot situation in which case you will probably die anyway. Add that to the fact it now takes time for you to start healing from a medipack, means you wont stand much of a chance.