I think it's kind of down to you to decide how you do what you do. 1. If you're comfortable with records, and want to go digital, the vinyl controlling a laptop thing is fully mature. The friends I know that DJ this way seem to like Serato the best. Traktor Scratch is a lot fancier -- 4 decks! Effects! Auto-beatmapping! -- but I think on the whole it's a lot fiddlier to use.
2. The M-Audio Torq Exponent thing has by far the snazziest looking controller, but I don't know anyone who has tried it: http://www.zzounds.com/item--MDOXPONENT 3. The Pacemaker thinger looks really teeny, and I think most people who are actual adults would prefer something that you control with broader gestures. And $850 is a lot of money for something you could accidentally drop in a glass of beer, or get nicked out of your coat pocket while you're trying to pull a girl... 4. The solution I've arrived at is idiosyncratic to me -- I use Ableton Live. It means that I spend a lot of time warping tracks, which can be tedious, but believe me it lets you really learn your tracks. Plus there a lot more options for effects, looping tricks etc, and with a decent midi controller, you don't spend all your time twiddling a mouse and staring at a screen. I can do a whole set and only use the arrow keys to select a track, and the return key to start it. I use an M-Audio X-Session Pro midi controller, which seems to work smoothly. One thing I discovered early on is to NOT map the transport controls, because I kept stopping tracks accidentally. I use them now to turn effects on and off instead, which is a lot less dire than silencing your set. This completely removes the action of beat matching from the equation -- if your tracks are warped properly they'll fit together perfectly. Now it's a valid argument to say "That's not DJing!" But I never practiced or played out often enough to get really tight with vinyl beatmatching, and nothing screws the musical flow of a set worse than a train-wreck. It's up to you to use the time and energy spent beatmatching to do something else musically useful and creative.
