My laundry list of reasonable suggestions
943 hours on this game and loving it. I do have some thoughts.
1) Shadows - the movement of my character's shadow seems to lag behind my actual movement (is the server sending me back my own shadow information?). It's particularly distracting when I'm prone because when I turn, my shadow turns a split second later and my brain tells me it's the shadow of someone sneaking up on me.
2) Weapon resting - is there a particular reason I can't rest my non-bipod weapon? Getting into a proper firing position is part of basic military firearms training. If you want to limit the effectiveness of doing this for a weapon without a bipod, just make it so there is an extremely limited threshold where you are actually rested, that turning slightly will remove the stabilized effect.
3) Lean left / lean right spam - I see this all too often as a defensive tactic to disrupt the aim of someone who's targeting the defender - it's kind of ridiculous (and not really effective either, as the center of mass stays exactly where it's supposed to be, but it does make headshots more difficult). I'd propose increasing the penalty for entering the lean state, as you can "waggle" about 20 times before there's any impact on your stamina - and no matter how low your stamina is, it doesn't prevent you from entering the lean.
4) Vehicle driving - it's just far to easy to spin out and flip vehicles. Nothing about flipping a vehicle makes the game more fun, and I don't think anyone would complain if it became very rare for vehicles to flip. It seems to me (wearing my "it should be easy to do this" cap now) that the weight of the vehicle is too low relative to the game physics, ie., could you increase the relative weight of vehicles and as well as their power output, so the law of gravity doesn't affect them in the way the game current dictates. Insurgent technicals feel like their tires are made of ice and it just makes driving them extremely comical.
4a) On the flipping mechanic, if we absolutely have to keep this, please reduce the timer on flipping the vehicle back, as well as adding a flip mechanic that moves the vehicle backwards or forwards by 5 meters. Frequently a vehicle will get stuck in a trench or on a wall or in a tree, and turning or flipping the vehicle will not solve the problem. While we're at it, there needs to be a flip option on helicopters, and it would be nice if defenders in Invasion could flip vehicles in the staging phase.
5) I'm looking forward to the mine changes in 3.2, but if the Combat engineer is going to get to carry 4 mines, then realism is going out the window: for the US faction, the M-15 Anti-tank mine weighs 14.3 kilograms, which means 4 weigh 57.2 kg, which for imperial types is 126 pounds. That's a lot of weight without the regular combat load on top of it.
6) While aiming down sights with a non-optic weapon, you can use the shift key to zoom in slightly, which is useful - but there is an unknown timing mechanic at play, some kind of ADS stamina bar, which gives you around nine seconds of zoomed-in time before you get zoomed back out. It's unrelated to stamina and I'm not sure why there is this arbitrary limit in place. Either tie it to stamina so you know how much time you have, or remove the limit (which would be my preference).
7) Weapon ranging - can we have the ability to do this while not aimed-down-sight? And can have the change "save" for the duration of the match? It resets on respawn. And for grenade launcher weapons, can the selected range be applied to all grenade types? It's differentiated between smoke rounds and explosive rounds (presumably because these are functionally different weapons in the engine).
8) Medic ammo bag - as a medic, I start with 10 patches, but I can't give any to other players when they run out. It would be awesome if the medic could be equipped with a medic bag he could drop that contained his patches, so other players could replenish their stock of patches.
9) Miscellaneous ammo bag - it would also be useful if every class had its own "ammo bag" that would allow you to give your own ammo to other players. Again, it doesn't make sense that I can't give a magazine to another player who has none. I recognize that both of the above changes dilute the role of the standard rifleman, but even if the impact could be limited to one magazine or patch, it would fill an emergency role that is kind of replicated by giving the ability of any player to patch another player.
10) Medic healing in vehicle - I see no reason why a player in a vehicle shouldn't be able to patch while bleeding, and while the medic shouldn't be able to heal. Project Reality's system was perhaps a bit simplified (players in a vehicle with a medic all heal slowly, and automatically), but it's perhaps the easiest way to do it; otherwise you'd add it to the radial bar, you'd have to select which player you want to patch, etc.
Otherwise, I'm greatly enjoying the game. My brief time with 3.2 showed me with 30 extra FPS, so I'm really looking forward to that!