A recent game saw me as Wang Kon (huge/fractal/18 civs) trapped on little 3-tile wide peninsula on the northern end of the continent, consisting mostly of plains and hills with a little grassland and tundra, but lots of seafood off the coast. I was able to found only two real cities (plus one more-or-less useless one to grab copper and a whale and one more size 1 city on the bottleneck of the peninsula). There was also a small continent 1 sea tile away where I built two more decent coastal cities; but America started on it and claimed the vast majority. In sum, I was forced to build only along the coast.
So to my south I had Saladin, who was small but quickly loaded with protective archers (and vassalized himself to numerous more powerful civs as soon as he could). To the east was Roosevelt, with a much larger empire and much better land. Shaka attempted to invade me twice, and twice MY protective archers and my hwachas in that little garrison city saved me. But a war of expansion was just not an option in the early part of the game. In sum, I had to find a peaceful way to keep up until I was in a better position to strike.
That's the situation in which I stumbled upon the WE. The point is, I snagged the Great Lighthouse and the Colossus, I whipped a castle in all of my cities for the extra route, harbors for the trade bonus, and markets for the specialists, (thank God I had so much seafood to help me whip and run merchants) and I sent my steady flow of GMs out on trade missions to keep the slider running at or near 100% science. I only worked a few cottages, because there was just no place to put them. For the most part I was working water tiles. My little Korean Peninsula DID have marble, so I got the Great Library too, which of course helped my science (I didn't pop many GSs, though, as it happened; the GMs kept coming). With judicious trading, I kept roughly even tech-wise with the most advanced AIs, some of whom were 4 times my size or bigger. At last (not until a little after AD 1000, if I recall) I was able to build/upgrade an army big enough to take out Roosevelt, then I intervened in a war on the third continent which started out as a nail-biter but finished with me conquering Egypt, vassalizing Monty, and taking half of Hannibal's cities. By that point I had plenty of land and was transitioning from this unusual economy to an orthodox CE in my newly conquered territories. Finally, I won a space victory.
Wish I had some screenshots, but I didn't save the game frequently (I kept expecting to die and move on to the next game), but I hope you can see the WE really saved me. Like I said, I really hadn't planned on it. If I had, I would have pulled out all the stops to build the ToA as well.
Mind you, this was just on the Prince level, so it might for whatever reason not have been viable higher up. And it was under VERY unusual starting circumstances -- lots of water, lots of seafood, little good land, neighbors too powerful for early war, lots of neighbors to trade with. I would not have thought to go this route in a more normal situation.
But when your start calls for you to hug the coastline, and you're feeling pinned in, I think it could be very viable. A Financial leader is probably a must. I think Wang Kon (Protective for cheap castles) or Hannibal (with the cothons) are the two best. Elizabeth could pump out the GMs faster, so she might be good for such a scenario, too. For Mansa it would be viable, but he has a good chance to get an early shrine, making such economic gymnastics unneccesary. Playing as Huyana would help you get the required wonders, and Ragnar would be fine too, but those two could probably just fight their way out of such a situation. Starting with fishing is also helpful.
Some final notes:
1) Castles, a much-maligned building, really shined in this game. True, they have a short life span, but that just meant I had to prioritize Engineering to get them ASAP. And they obsolete with Economics, but Economics gives you Free Market, which I switched over to immediately. So what they really did was give me the equivalent of FM shortly after I discovered Engineering.
2) The wonder obsoletions really hit me hard, epecially for the Colossus. Ironically, the WE is well suited to a pangaea or (like I had) an almost-pangaea fractal kind of map where you can comfortably delay Astronomy for a little while. But you've got to make your move eventually, and start conquering actual LAND.
3) Another thing that I didn't mention before, but which made this game so odd, is how few workers I built. You just don't need too many until later; you're working the sea and running specialists.
Yikes, that was long. To sum up: based solely on my one game and my limited capabilities, the WE struck me as a sort of mini-SE for Financial leaders with little cottageable land. For a non-Financial civ, I would have run a regular old SE, but this seemed like a waste for Wang Kon. If nothing else, it's taught me not to despair, as I used to, when I get a water-heavy start.