Due to the way this game is, balancing seems to be a hard thing to actually think up due to things like the duel gunners heal but I'm going to post my thoughts anyway.
PointMan: I think this class needs some sort of default HP or Defense increase in general, this class is barely ever used for the purpose that they're slow and hard to actually get kills with, so unless you're playing in a dedicated team that's working in synergy together and not for your own kills, then this class is quite underpowered, especially with the fact that the pointmans shotgun when your stood right next to someone seems to have a thing for not 1 shoting them when you're barely a meter away.
Recon: It seems their default gun is balanced enough, but when we get guns like the PMC-AK that has double the firepower...they just become the call of duty style 3 shot kill weapons where we all die instantly, also their head shot capability is off the charts due to how slow we move in this game and we have no sprint, it also makes it easier to score a head shot due to the recoil of the guns so if you just aim roughly around their head/upperbody area then you will be more than likely scoring headshots.
long story short, their guns need decreasing in power especially due to the fact that they can scope in for high accuracy while blowing your brains out in close range combat.
Sniper: This class actually seems balanced enough, they simply succeed in ranged shooting, they can survive in medium range only just, but if someone closes into you in close range combat then your usually meat, as it should be.
My only complaint would be that quite often you can be getting body shots to the point where you need to shoot someone 3 times to get a kill, I'm not sure if that's just latency or what but from what I've seen it's been taking 3 bullets to take some people down and that's with the 130 damage sniper.
Heavy Gunner: I don't have much of any complaints with this class, apart from the fact that when they're ducking they get a massive accuracy boost to the point that headshotting for insta kills is quite easy, I pulled this off my self fairly easy on a few levels I was doing and this was with the default gun, I fear to see how much easyier it would of been with their 73 attack damage gun.
(Edit)The RPG: I think this is only the heavy gunners weapon (no idea how you get it as I didn't see it in the shop) but this needs balancing by:
-Reducing the speed the rocket travels
-Reducing the explosion radius
-Reducing the damage
My reason for this is as we get some levels like "Two Room" for example, this has 2 bases and 1 route to connect in which it's usually being spammed by grenades which is bad enough, but instead we usually have heavy gunners that come straight out of spawn with their rocket ready and either randomly fire it into where people usually are (or about to walk into) or they wait on top of the box's at the spawn, wait for people to get into the line of site and they can usually get a guaranteed kill from it (if not a multi kill instead), if the maps were much larger (like CoD maps for example) then I could see no reason the rocket isn't the way it is atm as that game isn't based around narrow hallways like this is which makes the RPG too lethal.
Duel Gunner: I would like to say this class is fine, but we all know on some maps they really arn't with so much close range and corners to hide behind like the train level for example, I see a lot of medics on their just rolling faces because they can keep healing them selves up so it's basically a no fear class most the time I would like to say we either need to:
Edit for this bit, should of thought of this before:
-Make it so that the medic only has the ability to self heal like 2 or 3 times, but they can heal teammates and unlimited amount of times (or if need be, add the fact that with there 2-3 heals or so, they have to go back to the ammo box to replenish self heals so they can't stay in the field all day with infinite heals), that way they won't be overpowered solo tanks destroying everything in close range and healing during a gun fight all the time and they also keep their team usefulness on the field, it would get other medics to heal other teammates and especially healing friendly medics so they can stay on the field, it's a win win scenario.
-Decrease their gun damage by about 20-30% or so to compensate for the healing, or change how the medic gun works by perhaps either making the medic gun have a longer cooldown (which would make the medic a none team player as they would save the heal for them selves more than likely so possibly not a good idea)
-It could perhaps be made so the gun simply only heals up to 30 or 50% health per heal
-Or even just make it a heal over time thing, so when the heal kicks in it will heal 10% HP every second for 10 seconds in which that way we won't get medics healing in mid battle for full health when they get the chance while the opponent is nearly dead.
Headshot damage:What I would personaly like to see gone is headshot damage altogether, simply because it takes very little skill to do it and more often than not, it is totally by accident and seems to kill off player skill since most of this game is about spraying with your gun, I personally think it could fix some balance issues like with the duel gunner being so "OP" as people say as they have good damage and can heal, if headshot damage was took off then they would have to rely on the actual guns damage and not headshot spraying, the same goes for the heavy gunner 1 shotting people in the head with their gun and and the recon having very easy headshot capability in close/medium range etc etc.
(Edit)Yeah I possibly should of said that if not taking off headshot damage then the damage multiplier should perhaps be reduced instead to stop the insta kills by assault rifle for example, the only reason why I mentioned it is due to the strange fact that bodyshots take such a small amount of damage compared to headshots taking massive amounts, unless that's what the game is going for...if not then at least reduce it to bring some form of balance (especially to make snipers more viable for insta kills).
Grenades: Issues with the current grenades system:
-The grenade explodes far to fast to even react to it a lot of the time
-The explosion radius is too large (this bit is mainly bad due to how fast the grenade explodes)
-It does too much damage even at the grenades max radius distance
-There's no indicator and no noise when it hits the ground (or barely any noise at all), an issue with this is also the fact that the grenades explode far to quickly, so if you have noticed it and it's too late then you're out of luck.
-(Edit) Grenades need to stop doing damage through obstacles like trains, walls etc
P.S this is possibly one of the first PC FPS games I'm actually enjoying, the only other FPS I've really enjoyed is CoD and battlefield on my Xbox to this is saying something for me as I never usually give PC FPS games a second thought after trying them out once.