I also notice people tend to melee someone when they have already fallen over dead and also sometimes falling over is extremely slow.
Better to be safe than cocky considering all of the game issues...
I noticed most of the lag in uncharted 2 but uncharted 3 seems as bad or maybe worse. It does look like they would have matchmaking by region. If you see someone from japan or someone when MEX in there name there usually lagging. After the lag I've seen I know they must have took out the lag protection thing. I really think they should add it back but it shouldn't be as picky. It should just lock someone out with major lag.
Sony has no requirements for connectivity so long as you can return enough packets you stay connected and in the game even if your internet is having a bad day... or just plain sucks. This is Sony's policy so there's not much any developer (and not certainly not one owned by Sony) can do in regards of locking people out. (If you're curious Xbox Live does.)
And I'm sure its what you meant but missed typed... There is no regional matchmaking. Its why you see the Mex, CHLE, FR, JPN, and a few others that lag really, really bad and cannot really get away from them... Granted, each room is different. So if you find a good room you should try and stay in it.
As for the netcode being crap... Yes, and no. Do I think their code is the best written? No... and they certainly should have done regional matchmaking or at least given the option but they have one huge (errr small?) problems that CoD doesn't... Player base.
They don't advertise it, at least in UC3, but after UC2 players started drying up they use to only have about 2000 connected players connected at one time. Period. Across all game modes. And that's not enough for a game to be healthy and lag free. (Note: There small player base is why they patched it and went to the number of players in the last 24 hours.)
And I suspect by now that they likely have about that many people now... Maybe a bit more, maybe a bit less.