Tough call... if you look at U.S. Army examination of past battles, 90% of targets are engaged at ranges of less than 50m. Checking out the recent fighting in Iraq, the Marines report most engagements occuring at 20-35m.
For civilian use, you are even less likely to engage at range legally since it will be extremely difficult to justify a long distance shot as self-defense.
Using those statistics as a guide, I think the Aimpoint offers an advantage in both cost, speed, and flexibility of position at those ranges.
On the other hand, I think the ACOG offers a better ability to ID and engage targets even at less than 100 and that if every soldier or Marine had one, you would likely see the above statistics push out some. I think it also lets you scan urban areas a bit more thoroughly. Last year's SAM concept test in Guam seems to suggest that the BAC ACOG does grant an advantage at the fireteam and squad level.
If I was a member of a military unit working with others in a team, I think the ACOG would be perfect.
As an individual, I would think that using a rifle and ACOG to identify potential threats in an urban unrest scenario would cause more problems than it would solve and you will still want to keep a low profile and incidents would still be close where the Aimpoint would have the edge.