Well, there probably wonāt be an S6 (since the S2 is 2-deck and S4 is 4-deckā¦the S6 would be 6-deck?!), but there are some other power controllers coming out.
To answer your first question, the S4 is more than just a 4-deck controller, and the same can be said about the S2 being more than a 2-deck controller. They are beasts of controllers that are hyper integrated into Traktor software. They allow complete and total control of everything within the software. The S4 does this better than the S2 simply because of the availability of buttons/knobs/faders/etc.
Both the S2 and S4 are as portable as you make them. Iām actually fixing to buy the DJTT S4 bag so I can carry my S4, laptop, cables, and extra āstuffā wherever I go. There are other carry options available for both the S2/4 and other controllers, so donāt let that deter you TOO much!
If you are well integrated in your setup, you could probably do without the S4 simply because youāre used to using the X1/MF for other controls. That being said, I know some people say that an S4 + MF + X1 is controllerism bliss.
There are things you can do with the extra controllers that you canāt do with either the S2 or the S4 alone.
And it depends on what you mean by splurge. Again, if you find a used one or a good deal on a new one, the S4 will probably be the last major controller youāll ever need. Itās SO powerful and integrated, itās crazy. But Iām probably going to hunt down a MF for 8-cue point control + FX nutso time.
Now two things I want to conclude withā¦
First! Iām not trying to sell you on the S2/S4. In fact, I hope that despite what I put forth, you still go and do some extra research (be it reading articles or tactile fun). It sucks when you roll with another personās opinion and hate it later, haha.
Second - the S-series controllers are widely regarded for a good reason. There are other amazing options out there, but given how powerful Traktor is and how well integrated BOTH the S2 and the S4 are with the software, you canāt go wrong [if youāre a devout Traktor user like myself].
I had a little discussion with someone about the S2/4 when he was looking into them. He had the money for the S4, but didnāt want to deal with the āextra sizeā and was saying he wouldnāt āuse all the featuresā. This is fair, but the size of the 2 and 4 are very similar (similar enough where I canāt imagine it would break the bank on setup), and the extra features of the 4 are powerful enough to merit the extra cash. On top of that, the S2 is priced somewhat higher than I think it should be given the features it IS lacking.
I sound like a damned salesman, and I apologize. But if youāre a Traktor dude, you probably should watch the S2/S4 and work with those. No setup required, full software integration, powerful and quality buildā¦All of these things work in your favor man. 