I think the KillCam prooves that in reality everyone is playing the game in different micro time zones. There have been loads and loads of times when the KillCam has shown me not fireing a shot, when I know I have. Or I am facing away from my enemy when I know I was facing him when I died.
According to the guys rolling out the Cloud gaming services, 80ms the maximum time they have to work with before people notice the lag. I reckon a connection of 80ms for MW2 is a good one, so the KillCam shows up the massive latency there is in the game for the vast majority of players. I mean how many KillCams have you seen were you are being hit, because the crosshairs flash, but you aren't actually there you've moved. Or a headshot is actually a foot above your head, then there are the knife kills were you aren't even on the screen when the knife registers the kill.
It would help if IWNet only matched you with players in your own country, but when you are playing a match hosted by someone in Germany then there is no hope whatsoever of getting a ping of less than 80ms.
It's just a fact that dedicated servers are required for PC gamers, simply because they are more widely spaced out than console gamers. When my son plays on Xbox he is playing with 5 or 6 mates all on one team, they all live within a 1-2 mile radius of each other so P2P hosting works ok for them. The nearest person to me that I play MW2 with is 20 miles away, after that 25, so straight away the latency is increased.
We all know the reason for no dedicated servers is so they can charge PC gamers for DLC, rather than the commmunity mod servers to run custom maps and get them for free. So in a few months time we will find out for sure that this really is the case, when the Stimulus Map Pack is released for PC and PS3.