It's my experience that smoke grenades are your friend.
You can drop them at your own feet. This is more helpful than you'd think. They don't do any damage, and buy you time just as it can buy you time to lob other grenades about.
They compliment other weapons. If half your party is kitted out with area of effect weapons such as grenade launchers (or even just grenades in hand), you might find yourself in a situation where you can't use them without endangering your allies... unless you can drop a smoke screen so that you have time to get to better positions.
If you're relying on turret weapons, your characters will need time to kneel and deploy before they come into effect, and your martial prowess will suffer considerably until they do. Again, smoke bombs buy you time, though in all probability you'll need at least two smoke bombs to use this tactic if you're also buying time to move to new positions.
Too spread out at the moment? Salvation in sight, but danger all around? Smoke bomb. Enemies giving you trouble, and you've got the AoE weapons that can take them out by targetting ground in line of sight? Smoke bombs won't stop you from doing that, and your enemies might not be able to target you until they're clear.

I have to ask, does anybody have a different experience along these lines?

Well, nice tips, but I have to admit that I never used one !
I currently play AS (the best imho), I have a couple games running, but didn't finish the game, in the most advanced one I'm fighting the Wargots.
But regarding hand-thrown grenades, I think they're too long to arm and thow - the guys you target are on you by the time you throw it, and they're quite inacurate !
So I mostly use modified MGs with AP ammo, and sniper rifles. And only underbarrel GLs from time to time.
But your points are valid, smoke grenades are different, and could be of a great help when things go wrong, I'll have a try!

Good points as well. If they don't work for you, I'd love to know why not.
I did discover that attempting to cross a map under constantly moving, refreshing smoke clouds isn't entirely practical.

Yes, 'nades are too long to use as they are used in direct fire (eye to eye) here... So rifles are almost always better. I must use 1 grenade per map, and in a whole game up to 5 smoke grenades ..

Let's extend the discussion : in early-mid games - ie when firearms are still the top tech-, is there better than M60 MGs, XM8s and sniper rifles (L115) ?
Other MGs are clearly worse (well the PKM has lots of ammo, Minimi real sucks), Barretts are too heavy and long to fire, GLs, Flamers and LAWs are too short ranged (plus LAWs dont have HEAT rounds, go figure!).
Lasers are bleh - good accuracy but damage output is way lower, Sonic, well, didn't use them much except sniper rifle (good for instastun). Did I miss something, or does the game revolves around these few "best" weapons" ?

To make short: No better. But later will happen the warp weapons.
Lesser weapons are to use other ammos, as often on a mission you don't need the better weapons.
Other weapons are good too against specific targets (energy are good against mutants), or for special missions (lasers are good to capture without heavily harm).
So, for each mission, you must think about kind of mission and enemies, what weapons, how many, and what ammo to bring with.

Ok thanks ERISS
Mutants aren't much of a threat when everyone has ARs and MGs, the only difficulty is to *capture* those damn weak Muckstars ! :-) I didn't try energy weapons vs Wargots, as they seem to react well to 7.62mm AP rounds ;-)

I didn't get Warp weapons yet, but was wondering what are worth Plasma and Railguns/Gauss weapons : should consider they're mostly useless ?

You seem to play with ACM mod. It is very different from vanilia.

No ACM Mod for me, but "Weapon Rebalance" (which seems more akin to vanilla).

My experience with smoke nades was extensive in UFO:Aftermath back in the year it first came out. It was the first tactical game I played (didn't know what XCom was at the time) and I used smoke grenades all the time to cover my guys when taking fire and buy time to spam frag grenades.

Smoke grenades were a smokescreen for my lack of skill at the time, to put it bluntly. Handy yes, even nowadays, but I don't rely on them as a crutch near as much as I did years back.

In UFO:AM, the grenades are amazing. I didn't use the smoke grenades much, but I think if I had, then things would have been easier.

In UFO: AS, the grenades all suck, except maybe the incendiary ones. But you're more likely to hit yourself than you are to hit the enemy, which is why I'm always glad to see Wargots with grenade launchers.

I will say this, though. I love the Barrett sniper rifle. Sure, it's less accurate and takes longer, but you can take down the most heavily armored foes in the game with it. The laser sniper rifle is okay, and really good to have when the bad guys get somebody who resists bullets, and warp weapons are almost necessary to win.

Also, the damage output on the PKM is (I think) slightly higher if you can get it to hit often enough.