Too late to take back my previous doubting statement?
I just did a near perfectly timed Factory rush and absolutely KILLED it!
-rushed Industrialisation popping 2 RAs and a GS near the end..
-had saved the cash to buy 3 factories within 2 turns of Industrialisation..
-timed the World's Fair and got top contributor the turn after I bought my 3rd factory (so Golden Age + policy 2xculture) in addition to rolling a policy that turn.
-opened Freedom for the 2 free tenets and used the free policy to get Level 2: Volunteer Army tenet all in the same turn.
Standard Emperor game, Standard speed Continents... turn 219/1540 AD...
While I cracked wise about being ahead tech wise obviously giving a military advantage, in practice this approach gave me the 6 FL (which others mentioned are strong Rifles/weak GWInfantry depending on your perspective) at such a stupidly early point -1540 AD- when I didn't even have Gunpowder researched!!
I used these 6 FL to immediately rush Attila (since no-one liked him), take his cap, free 2 City States, burn another city for giggles, and get a fat peace deal... with NO siege along for the ride (technically one crossbow, I guess). I could easily push this might on at least one more civ but everyone else is Friendly as heck so I don't want to push my luck.
Suffice it to say though, played right, this strategy can be utterly AMAZING.