Oh my god, easiest map, if you are willing to work for it, it gotta be the Wasteland. You just hide, let the snipers get all setup. You know they general area they setup on, also the routes they like to take. You can kill them while they are busy looking in the scope, or while they are in transit. I have so many games on that map with scores of 15-25 kills, 0 to just handful deaths, mostly just sniper hunting. Talk about a k/d booster.
I'm starting to get back into MW2 properly now, but one thing I forgot, is how much the killstreaks add to your kill tally, and artificially inflate your k/d ratio. The other night, playing HCHQ Pro, I finished 55-7! 41 of those kills were from the predator/harrier/chopepr gunner.
I don't know about "artificially" anymore. I used to think that, but unlike CoD4, kill streak rewards have pretty much become part of the game. But bottom line, yeah, that's how you can boost your kills. Especially if you are just "OK" player like myself.
I had forgot about jugg and how much I hated that perk until the other night I was playing COD4 and kept shooting people with my sniper set up and just getting that dumb hit marker

What is even more annoying than jugg is painkiller......
Juggernaut never bothered me, only except when I used it, and I seem to drop at a normal rate.

Painkiller on the other hand, I don't know how many times I got killed by it. That thing is worthy of being part of the (death)streak reward. It's like they got a vest on!
I now prefer the AA-12 to the SPAS-12. I will continue using it until I unlock Extended Magazines on it. I will then probably switch to the M1014.
I like all three, but they all have pro's & con's. In tight maps, (really)close fights, AA12 is near impossible to beat. Especially going up against groups, if you conserve the ammo in your clip, you can easily take out three guys with one clip. That's really good for a full-automatic weapon. Reload is one of the quickest around, too. SPAS is amazing in close-to-midrange. While they are trying to put the rounds in you, you just drop them literally instantly. Honestly, SPAS is the shotgun I fear the most(from the receiving end

). The range & accuracy is deadly. M1014, I haven't figured out yet. Range is good, power is good, but I haven't experienced or seen the effectiveness of its' stopping power or the range in combat yet. Could be that I'm not using it right, or my connection was slow, I don't know. It is clumsy & slow to use in tight, close firefight, that much I am sure.