I think the Distortion / Overdrive effect in Caustic is really smooth and awesome....
But did you know that you can have even more flexability and tone shaping contrtol over your sounds?
IFX Effect Block 1: ParaEQ
IFX Effect Block 2:Distortion (Type Saturation)
Machine Channel Strip EQ to compensate and balance your final tone.
The ParaEQ is used for pre-gain tone shaping control of your signal into the Distortion /Overdrive Effect. Sometimes sending more of a Low-end shelf frequencies will yield a smoother thick Overdrive effect..... while in other cases sending more of a High-end shelf Frequencies can yield a more clean or crisp tone to your Overdrive effect.
Then use the machine channel strip's EQ to balance your sound so it sounds the way you want it in your mix.
I have used this method for instrument and cabinet modelling, especially when feeding tube pre-amps ------ EQ --> Tube PreAmp and Drive Effect --> EQ --> mix