I tried this strategy last night on Immortal. I think I still need a bit of work to quite master it, but Im impressed.
Playing Poland, I have Russia to my south, Netherlands to my east, and England to the far east.
I was a little put off at first as I was unable to find any settlers to steal for quite some time. Russia had one, but it was guarded by 3 warriors. I had to steal one from a CS at turn 30, which is really late in the game to get a first settler (from what Im used to). I was questioning this strategy at that point.
Still, I left a scout near Russia to see if an opportunity would arise, while I explored with the other settler who had an archer upgrade.
Around turn 40, my archer scout found a new CS who had a barbarian camp harassing him. I took that out and got friendly from the quest. Then I saw a barbarian had taken a settler. Took that out and swiped him.
At the same time, a camp popped up near Russia, and he sent his warriors off to kill it, leaving his capital open. Just as I moved in to take his worker, a settler popped. I took his worker, and the next turn took his settler. All with a scout! I made a nice clean escape as his warriors were to busy fighting barbarians. Peace offer came 4 turns later.
So now Im sitting on 5 workers (1 from policy) and 3 cities at turn 55. I have the warmonger label, but nobody seems to care. Im neutral with all the other civs.
By turn 70, I had my 4th city. I have 6 archers. Russia was crippled by my swipe, only at 2 cities now, and his score is half everyone elses.
I cant wait to see how this turns out. Im running a small deficit and behind in science, but with my 4th city down I can focus on economy and getting NC. Meanwhile, Im going to get friendly with England in the hopes I can eventually use them to squeeze Netherlands from both sides, but before that Ill probably take the hammer to Russia and secure my half of the continent. That will depend on how well Netherlands does, I cant let them get to strong. A limited war to knock them down a notch or two might be prudent.
The downside of this strategy is that all these workers and archers cost a lot of cash. Im running -5gpt, but Im able to keep my gold around 150 by taking huts. Its a minor downside that is easy to fix once you get your 4th city down and you change focus to economy. Not building workers, ever, is amazing.