Hey
Ive recently done exactly what your doing now so ill give you my thoughts. I needed an upgrade and went for an S2.
I cant comment on the Pioneer so someone else below with have to give you their thoughts on that. I can tell you what i think about the S2 though.
The S2 is a great controller for the price (i got the Mk1 when the price dropped). It does everything it needs to do. It was the first time I had used Traktor and since ive learnt alot on it since, im blown away with the power of the software itself. I also got alot of remix decks samples free with the purchase too which i thought was pretty cool.
If i had my choice to make again, i would probably have waited an extra month, and gone for an S4, purely for the extra 2 channels, extra 4 cue points (8 – S2 has4). I believe it has extra inputs too, although i might be wrong there. The reason i would of gone for an S4 is because i like to use alot of sound effects, drops, loops within my mixes, and although the S2 can do it (using the remix decks) its alot simpler to do with the S4. Of course however its alot more money.
If you think your going to be mainly using the 2 channels only, i couldnt think of a better purchase to be honest though. The integration with the software is second to none as well as its NI own.
I use Audacity quite alot, and i see how you mean about using it as a workaround for recording and saving money, but honestly, id go Traktor instead.
Just my thoughts 🙂
All the best
Buttkick