I havent tried dual pistol but i have a Rad Rad corr and def both 50. The rad offense set (Radiation Blast) with the exception of AIM reduces enemy defences, the snipe is powerful enough to do serious damage and act as a third major debuff in the face of a big bad monster. Irradiate is too much of an aggro draw for me so I dont pick it. electron haze is skipable too as cones are such pains to make work effectively. Cosmic burst is extreme damage. Neutron Bomb is a ranged mob debuff and damage...that blows up as a mushroom cloud! whats not to love!?
Atomic Blast doesnt seem to be bang for the buck with making sure that tough, weave, and maneuvers are all helping with survivability and anti-squishiness.
Rad Rad corr can solo better than the defender but not by much. Just remember, you are NOT a tank. Must control the crowd. 
Pros and cons of each combo? Which is better for solo activity?