Being in purge's "premade" i can vouch that we all have good connections, heck im running 5 mbits up on fiber. In a 5v5 game network traffic is minimal and didn't even use 10% of my connection (used a bandwidth monitor). All of the guys in the premade have at least 1 mbit up.
In Purge's defense there are definitely issues with networking, however in Stardock's defense (I believe they assisted in the rewrite of the netcode) there are a lot of things to take into consideration.
Even in the best case scenarioss, sub 100 pings and 1mbit+ bandwidth & stable connections there are still issues out there on the internets that cause lag. One thing that I have noticed in the real world that cause the most problems are cable connections. They are inherently unstable and dropped packets are a norm. I'm not a network architect so i dont know what the causes are and what the solutions can be but i know that it is certainly challenging to be able to compensate for that network behavious in a mere game.
My company had a DSL connection at 1 office and a cable connection at the other office, pings were great (sub 40ms) upload bandwidth was acceptable but the connection between the two sucked. We had to install a software package on our exchange server just to be able to keep the connection from dropping every minute (literally). The cause was the cable connection, the solution was to get off of cable.
So i don't know who is to blame, bad netcode? or netcode that could be improved for adjustment for packet loss? perhaps, cable connection stability issues? im sure that adds to the problems.
For this type of game (I forget what Frogboy called it, but this type of game versus a traditional RTS) some sort of client server set-up probably would have made a more enjoyable experience in regards to the gameplay & lag. But there there is the significant added cost of hosting the servers, who host them, how can they be mainained to prevent exploitation etc.
On other notes, wireless almost always lags.
COD MW2 is not using the same networking system that demigod uses. It's not true "peer to peer" it's still a client server relationship with a 'capable' host and wont use dedicated servers.
I wonder how well the MW2 system will work, but alas i wont find out. My ass still hurts from the rogering the Infinity Ward has given us PC gamers so this will be the first COD that I haven't purchased and played religously. (COD3 doesn't count)