Generally the magazines are saying that the '02 is what the ZX should have been in the beginning.
The earlier models have less extreme ergos, slightly lower saddles and higher bars. The advances on the '02 include suspension (no more front-end push, probably slightly stiffer front end), enhanced midrange and low end, smoother motor (that crank again...).
Fairing is redesigned, good and bad. Bad part is that you can't find a double bubble for the later model.
Have a look at www.motorcyclenews.com, under bike reviews. They have a few tests and comparative tests across the years.
You will find left over 00s and 01s at bargain prices. Right now in the north east, I can find more 01s than I can '02s.
A friend's sister bought a leftover '00 a few weeks ago for $7.5k. Her husband bought a used '00 for much less than that, I think $6.5k in spring.
Unfortunately she totalled the bike a day later.
Apologies for the wordy reply: I started off researching CBRXX versus ZZR12 versus FJR versus the ST13 a while ago, and am probably going to acquire an '02 ZX12 this week. I had a look at the sport 1000s as well.
Part of the negotiating is persuading wifey I need more than one bike. The original premise was that I would sell her F650, the R11GS, the Concours, and the parts Concours, and get one nice allround bike.
Now it looks like I will keep the '01 Connie for 2-up and touring / bad weather commuting, and have the ZX12 for fun and fun commutes.
The GS is being sacrificed (no loss).
Of couse, the Connie is rather an industrial, underpowered, saggy old thing compared to the ZX, wonder how many miles it is going to see?
It is pretty comfortable and protective though, and the owners club is great.
I have been considering an 02 12. I've heard conflicting reports on the smoothness though. Is the 02 really smoother through that 4~5k rpm
And is a 00 pc3r compatable with an 02 or do you have to get a pc3r for the 02?
Don't Forget about the improved clutch design that allows more oil flow in the '02 models. I have the '01 green bike with the rad factory decals but the reliabilty of the clutch has me worried. I don't drag race but I do tach it out in the lower gears like everybody else.