That is a con of the idea, but I think it wouldn't happen too often. It's more likely it would benefit solo players rather than players on a team.
Well, I don't think it would be extreme, but that is somewhat the point. If he takes out your teammate, he deserves to recover some health to help take you out. If it's 2 against 1, that means it's 2 swords vs. 1 sword, 20 hearts vs, 10 hearts, 2 sets of armor vs. 1 set of armor. I could go on, but the solo player should be able to recover 3 hearts if he doesn't lose his own 10 first.
Although it may be unfair to many, I think it will benefit most. You have to see that most people who player MCSG are people who solo. Also, I don't mind if people don't like this idea. I even encourage arguments so that I may see how the people who oppose the idea see this idea. However, I do mind when all they post is "This sux," because I've stated multiple times that such a post is useless. It doesn't help me see why that do not like the idea so I can get a better understanding on a flaw the idea might have. I'm not hounding people because they don't like the idea. It's because their post does not give me another perspective on the idea.
So should this only be implemented in TSG3?
I'm kidding haha