Reply to Used S4 versus S2.

As some people know here I am trying to get back into DJing, being largely absent for 12+ years other than some occasional laptop mixes.

I have been seeing some S4's at some descent prices as of late, and am curious if mixing on 4 decks is worth the additional cost or if I should just invest in the newer S2. Are there any advantages to the S4 or S2 that would put either over the top?