Man its not about what you have its about how you use it! I've seen people play dope sets with nothing but laptops, no controllers or anything. You just need some buttons to press and you need to know what you're doing (but I'm sure you know that if you're thinking of going the ableton route).
If you use traktor build on your DJing skills, ableton is a completely different program and isn't the same. Traktor pro is a huge incredibly powerful program, there is no way its limiting you, pros use it all the time. Start really learning the features and you'll be blown away at what it can do, there's a reason guys like laidback luke don't need anything more than turntables, and its because they make their gear work and perfect their art.
Depending on your budget, go with a pair of CDJs and a legit mixer. It would be taking your traktor setup to the next level... But you really don't need anything more than traktor and a nice specialized controller. You can have like 4 decks going, tons of FX, chop samples in realtime... It does crazy things. Ableton would also set you back SIGNIFICANTLY because you'd have to learn a completely different way of mixing, and you wouldn't be playing shows right away.
IMO the best way to do things is to make your own setup by programming different controllers to do stuff... Thats the way everyone is starting to go anyways, DJing will still be around but Ableton and APC40 is a basic version of the controllerism you see people like the Mau5 and PL doing. Way harder but seems like more fun in the end.
That denon controller reviewed well:
Probably can't go wrong.