I don't think it's really needed. The current balance is far from perfect, but it is way better than anything that has been suggested until now. Combat shotgun can be countered - and cops forces prove it.
In fact, deagle driveby is more powerful than minigun, because the damage is equivalent, but deagle's fire rate is significantly higher. Submachine guns are main weapon in close onfoot combat, but UZIs deal more damage than TEC9, thus, given opponents' equal skills, cop should always win. Cops have M4 with great range, so give terrorists M4 instead of AK47. And... end up with absolutely same classes. Well, this seriously could be an option to balance the game, but I don't like it, and I guess most of the players wouldn't like it either. So, -1 to this suggestion.