I have played 100+ games on Noble, and win probably 2/3 of them. However, I have NEVER gotten what I would call a "decisive win" - that is, where I simply trounce all or most other civs militarily. (unless I do something like a very early rush against 1-2 city civs, which is boring after the first couple times). The problem seems to be is simple logistics - you can't move units fast enough across long distances. You send a herd of swordsmen to a city 15 turns away, and by the time they get there tech has advanced so much that he now has Muskets. So you make Muskets - and by the time they reach that far away city (ever worse if by sea), he has riflemen. etc etc etc. And if the game goes long enough to get to modern armor and mech infantry, forget it - by then both sides probably have tons of defensive units in their cities, and will probably have maxed out the culture defense bonuses also. So if the other civ has 10 large cities, you might need 150+ modern armor + artillery + gunships to even take half of them.