The CPW is pretty much an upgraded version of the MP9. It is a high rate of fire, medium damage SMG just like its smaller cousin. The SMG provides good amounts of shots downrange even with the long barrel. I suggest using a long barrel, grip, muzzle brake, and the medium barrel. I chose these mods to maximize control and accuracy. Even with these mods, be sure to stay at close to medium ranges because the gun really starts to lose effectiveness the further away you go. Be sure to add an extended magazine, and a good close quarters optic. It is a good weapon for flanking, like most other SMGs.
Flanking is a good idea when using this gun. I suggest using cloak to close the distance and get around people, where you can tear through the enemy team from behind. The extended magazine will allow you to get a couple kills before reloading.