Reply to I can't decide between S2 and S4...

I already kind of made a thread about this, but I thought I'd get more precise feedback here.

I'll be upgrading from a Numark Mixtrack Pro with Traktor because; no hotcues, no sampling, tedious loop cancelling, and very tools to utilize effects.

If there is a thread that directly compares (like lists) the concrete differences between the two, I'll just delete this.

But if anyone could, point out the differences between the two, or even give advice on what you believe would be a better upgrade from the Mixtrack. My budget is fairly limited, but there is a "month old used lightly by an adult rarely" S4 on my local craigslist for 700$.