You say Clear Sky is combat-heavy, but is it good combat? I complained about having to kill tons of bandits/mercs/military/Monolith in SoC, but truthfully I enjoyed a lot of it, primarily because of how much freedom the game offered in tackling the various objectives. So if the gunplay is good or can be made good with mods, and the map design works, I could give CS a spin. I still feel the need to play a "realistic" FPS, and don't see any alternatives. CoD and BF make me vomit with their linearity and extreme popamole.
From what I recall, gunplay is worse at the beginning, unupgraded weapons have shit accuracy plus buckshot and pistol rounds (pistols, MP5) tend to literally disappear into thin air while travelling.
Damage, however, is higher, so is penetration. Upgraded weapons are quite pleasant to use and heavier ammo can actually penetrate a lot of things you or your enemies may want to hide behind.
Also, it features cover system... exclusively on the AI side.
Problem, popamolers?
Apparently in soviet Russia moles pop YOU.
Do try it if you can live with it being even buggier than unpatched SoC and with it being blatantly unfinished and ending with atrocious linear shooting section compared to which rooftop sequence in SoC is pure, untainted pleasure (no, I'm not joking). Other than that and other mentioned stuff the game works pretty well, it also features nice faction system. It also has really costly upgrades and repairs, so with some artifacts being so rare you may only see one of them in the entire game it can be pretty harsh economically.
Upgrade mechanics is pretty limited as it essentially either forces you into one of two paths (CQB or sniper with weapons, combat or anomaly protection with armour), the alternative being inability to upgrade the item fully.
Ah, one more thing, you'll need to mod NV immediately to CoP or SoC standard because original NV is useless and atrocious (looks like in HL:OF NV, except it doesn't provide any help in actual low-light conditions) .