Reply to Upgrading from a Numark Mixtrack Pro.

I've been digital DJing since summer, but only really got serious with it in the last 4 or 5 months with a Numark Mixtrack Pro.

Eventually I switched over to Traktor and realized with the Mixtrack; I don't have hotcues, awkward loop mechanics, and limited effects, NO sampling. And the mixtrack has become to feel more and more like a toy, The EQ knobs are getting loose too.

In the mean time, I borrowed my friends iPad, learned TouchOSC and used that for hotcues and sampling. But my friend wants his iPad back soon, understandably, and it's not really in my budget or interest to invest in an iPad solely for those purposes.

So, what do you guys believe my next step is? I was believeing of maybe...

Getting an S4, because it offers everything I'd need for quite a while, and with the money I have now I can nab a used one on my local craigslist. I'd like a new one, but I don't currently have the money and it's pricey.

Getting an S2, because of the crazy deal on it lately (either this site, or djranking s has them for about $400 with a bunch of perks). But, I feel than what they cut from the S4 for the S2 is what I wanted; the sampling, filters, and overall interface. Is it just simply redundant to go to another two deck controller at this point?

Finding a using NS6, pretty much the same reasons as the S4, if I decide upgrading to a 4 deck controller is the best route to take. Does it work as well with Traktor? Pros and Cons versus the S4?

Getting gadgets that compliment the Mixtrack Pro. I've just recently decided I want to learn to produce a little bit and would like to get in the swing of things with pads, effects processors etc (I don't know jack about any of these). Looked at some akai stuff, looked into Korg kaossilator and kp3, both seem incredibly overpriced for what they accomplish.

Other, enlighten me, my budget is at a maximum of about 700$ if I can sell the Mixtrack for like 150. I'm pretty new to all of this.

Thanks!