Despite the tremendous help I received for my PMC campaign idea, I have to scrap that due to some serious budgeting I have to commit to for the next few months. All is not lost though, due to the price of 15mm miniatures, and my recent infatuation with the Boondock Saints. Rebel Minis has cool Irish hitmen miniatures for a bargain price. Couple of civilians and mafiosos and you've got a game. Paper maps aren't bad for a quick game :)
I've considered a few systems for a campaign based on the movie, including Hero (a bit too much work), Unknown Armies (too lethal), Feng Shui (seems ok) and Wushu Open (it's FREE!).
Hero has built-in miniatures game play to its advantage, decent mechanics, and the option to fiddle with special powers as much as anyone can stand. It's a good option, but for a game based on half-assed plans and tons of luck, it seems somewhat restrictive to imagination.
UA is so simple and straightforward, with the option to implement some sort of magic into the backstory, that I had to consider it. A lucky roll from a mook that kills the protagonists doesn't really suit the flavor of the movie though.
Feng Shui actually seemed like the obvious option for this sort of game. You get to count bullets and do stunts and mow down gaggles of mafiosos, and the mechanics are pretty straightforward. The rules don't support miniature play that much, sadly.
Wushu is an unconventional option, especially when you consider running it with miniatures. The times I've played it, the narrative took on a life of it's own. You could still use paper maps and miniatures with it, implementing simple rulings about map zones and placing the miniatures accordingly (usable for Feng Shui too actually), and winging movement, counting bullets and everything through the descriptive game play. Also, Wushu has numerous options and hacks to mold it into a more conventional game if one desires it.
So far, that's all I've managed to scrounge together for this concept. Like in the movie, style over substance will probably be the emphasis of the final game.