IF you’re sure you will stick with your controller to play out, I’d get an certified mixer, as it can live where you DJ and you don’t have to lug it to gigs - else get an A10 as it’s more portable
As you (OP) already said, portability is the only advantage of the soundcard. I don’t think anyone here can determine exactly how important that is for you.
Get the Audio 10 or 8.
Certified mixers are great if you can get the chance to use them but if your doing a gig and using the club/bar turntables your unlikely to be able to switch out the mixer (unless its just you DJing).
Certified mixers are neat. No soundcard is great, especially when you can use FireWire although most are USB but…
You end up with an £800 mixer in your room which is cool but pretty much a waste of money… I’ve used my Korg Zero4 at ONE gig and that was cus i was hired to do a 30th birthday party otherwise its just a colourful addition to the light show in my room.
It’s one of the reasons I use my VCI in place of a mixer when I’m using DVS - if I can’t get the TTs to play nicely with Traktor, I forgo scratching for the evening and revert to the VCI …
I love my setup because all i need to take is my soundcard, laptop, x1, and some cables. Just plug the 1200/1210s or the cdj 1000s, that most GOOD clubs have, into the soundcard and youre sorted..