If you can afford em mate go for the CDJ-1000s.
They not cheap (about £750 each) but you certainly see where your extra money went.
I've had mine for nearly 3 years and I love em. Used to be a die hard vinyl junkie, and was really dead against the idea of digital mixing.
I got mine because getting hold of psy on vinyl was both expensive and quite hard getting the tunes you want. If you're used to vinyl then the 1000's wont take you long to get used to at all. Making use of the cue points makes mixing even easier, as you dont need to find that right point on every track each time you want to play it, only the first time, and then you store it in memory.
I've played a little on the 100s, and while I think they are good, and often used out and about, they're not as feature-rich as the 1000's (But I would say that, being slighty biased.

)
For example, the 1000's come with a nifty wave reading of the entire track so you can visually see where all the peaks and troughs are in the music. (You can zoom into it too!)
The pitch contol when set at +/-6% allows for 0.01% increments on your pitch scale (I think the 100s only does 0.05%? Somebody else who owns some may be able to confirm this? Haven't got a clue what the 800's do though?)
The 1000's are set to become the defacto standard for clubs also. As the 1210's set the standard for turntables.
My advice would be, whatever you go for, select pioneer.
Hope this helps?
CH
PS Not another aspiring DJ FFS! :P