Eh. I didn't mind it. But having it in our out definitely affects the ways you have to balance the game. Some combos become far too good. On the flip side is that by nerfing the combo, you invariably nerf the individual weapons so they're not even usable unless you're dual-wielding. Which is awkward, because then nobody would use them so they'd never be around to pick up and dual-wield making the entire point of putting dual-wielding in the game ... moot.
So, yeah. It'd be doable, but the entire game and weapon balance would be far different than it is now to include it. Plus it'd be just one more thing to complain about that "dual-wielding should be viable. Stupid DMR."
Dual weilding was okay in campaign. I used to use an SMG and a magnum. I would use the SMG until i needed to be reloaded and while i was reloading it, i would fire with the magnum. It let you lay down constant fire without having to find cover while reloading.
It was almost worthless in multiplayer though, since you couldnt melee.
Everyone said it a was a miracle when Jesus hit that grand slam in the bottom of the 9th. I just thought it was a lucky shot.