Is the Negev viable now?

Under gn4 - perfect troll gun, easy to play with and lots of fun
Above mg1 - it will be awful, just don't even try.

Not even the mp7 is a good choise, you should get the ump/mp9/mac-10 as those have a better money/stats ratio (I am talking about accuracy, armor penetration, damage, etc.), is just not worth it to spend that much money on it.