Good subject this.
I think 3 decks has the potential to sound totally awesome - it's the way you can layer sounds, play hats or pads of one record with the bassline of another etc, and keep the texture of the sound consistent. It also means you can have a more individual sound as a DJ - which these days is pretty important seeing as every man and his dog is doing it. My favourite DJ's all play on 3 decks, I just prefer the way it sounds.

I'll contradict myself though by saying that the guys who play well on 3 decks generally sound totally amazing when on 2 (check out Ben Sims on 2 decks). And it's definately better to play a tight set on 2 decks than a wobbly one on 3 (if the DJ/PA/monitoring are not up to it).

Finally, I think practising on 3 steepens the learning curve sufficiently to make you much better when/if you go back to playing on 2. It's the way forward! At the end of the day, it's how it sounds that's important and not image/showing off etc. The punters on the dancefloor will always vote with their feet!!