Reply to Help!! Is it worth buying the S4 or should I go for the S2?

Hey everyone. So I've decided to change my DJ set from Torq to Traktor, which seems to be much better. I want to buy also a Traktor controller, cause all the djing I did was just with my Mac.
I've seen some posts regarding the S2 vs. S4 but some say the S2 is the best, some others say the S4 is definitely the one, so I'm not really sure yet...

People say the S4 is huge...but is there really a big difference with the S2? Also, is it that bad that the S2 doesn't have filter knob? And finally, I really like adding samples to songs when djing just to make my mix more dynamic, so is it really necessary to have the extra 2 decks, or can I work my way out with the samples in the S2. In general, between the S2 and S4, which one would you believe is the best to go with?

I don't want to make the wrong decision and then regret buying/not buying one of the controllers. I'll appreciate your help in my decision!

-A