The special thing about Renegade X is, that you have a huge health by low damage. Compared to other shooters you survive much more.
This fact make a one hit charakter even stronger, because it doesn't matter how much healt you have, if you are just one hit. You'll maybe say, that some characters can survive 1 shot. That is right but it doesn't really matter a guy like @poi can hit a second one without a problem.
The second interesting thing is that the Players are smallers. So it is more difficultly to hit anyone, but the other thing is, that people with good aim and tracking are better. That is in every game like this, but for the other player with bad aim it is through these small characters almost impossible to get a good hit.
So how can we fix this?
Make the charcaters bigger, isn't a good idea (if that is possible). It would mess up the whole game, you need to make tunnels, buildings and bunkers bigger, otherwise they can't walk in it. It would take months to do that.
Nerf the damage. If you don't think much about it, it sounds like a good idea, but it isn't one. Imagine, you got a headshot on a character and he does not die. That would be very frustating and would make a sniper usless, because he can't get important kills. But maybe keep that in mind, I think a little damage reduce isn't a bad idea.
Now look on these 3 1k charcaters. The special thing is, that they are all like infantry tanks. Infantry tanks with a one hit weapon. I really don't know how the guys from C&C Renegade included this thing, that is fucking stupid, but ok. Think about an amor reduction. But that isn't that easy, to create a good balance there. I think, the main idea about the use from Sydnes and Raveshaws was Anti-Tank. So you need to watch out, that you don't reduce the amor too much, otherwise the tanks will kill you and you are not really an Anti-Tank unit. About Snipers: Give them so much amor is, as I said, a fucking bad idea. Snipers are people, who stay in the backline and not in the main fight. So there is no reason, for giving them so much amor. An important thing in balancing is, that if you have a pretty strong character, you need also a character to counter it. And how can you counter a very good sniper, if you aren't a good sniper? You need to get close to him. The problem in RenX is:
They have so much health
They can use their long range weapon also in close range
They have a strong MG for close range too
Nobody exactly know, where the sniper is
So I'll just say you, what I would do:
Give them a higher spread. Look at for example on Warface.
Give them a silenced pistol (or maybe Deadeye get a silenced, Havoc a heavy)
make their shots more noticeable
With the last point I mean, louder sounds and more visible shots. Look at Widowmaker in Overwatch. And who isn't playing Overwtach a little explanation what I mean. If a sniper is shooting in Overwatch, it is shooting a normal shot, but it looks like a fucking ion canon beam. So after the first shot, everyone will know, where you can find this sniper, and that is the first important step if you want to get rid of him.
I think I said all what I wanted to say.
But I can understand @Algol a bit. When I'm getting killed by @poi again and again in base, I'm really tilted and I could wirte things like this, too. But if you want to make a game more balanced, you can't win with screaming and insults, because nobody will listen to you.