I think you might be a bit ahead of the times for this forum matey. Traditionally dnb has been played out on wax, only recently have many people here been making the switch to DVS let alone ableton for playing out.
Ive messed about with it a bit myself in a DJ setting at home and now use it for production.
I couldnt get on with it as a live set tool, if I play how I usually play on records its well boring because ableton is doing pretty much everything apart from picking the songs for you. You can even make it do that if you want.
I think if youre planning to play out live with it, you should be looking at what people are doing with mpc's, lots of live drumming and on the fly remix's. This sorta thing is fine for noisia and deadmau5 who are producers and are only playing their own stems of their own work mangled together into some sort of live cluster fuck of sound. But for you, as a DJ, playing out other peoples music, its a different ball game entirely.
You should also have a think about what youre gonna do if you want to play out. I know many promoters that would shy away from an opening DJ bringing a full ableton rig & apc 40 simply because they dont understand it and think it'll go wrong.
Youve also gotta fit all your gear in a booth thats already full of gear, and be able to set-up / teardown within 5 minutes whilst 3 or more uneccesary people crowd the booth. Can you do that?
You should also be able to spin on anything that gets put in front of you, what happens if youre lappy goes down and needs a re-boot?
Personally I think its nice having your lappy in the booth, you get loads more information about whats going on which makes spinning easier, especially when there are loads of distractions about. I even think your own gear is more reliable than pretty much any club Ive played in. Most of which have broken TT's or badly behaved CDJ's.
So good luck, and have a backup plan!