One suggestion I may have, DD recently added a FCR carb, which is great for throttle response and power. The DRZ400E comes standard with the FCR carb and also larger header pipes. Lots of guys have road registered E models, so see if you can find one. E model also has slightly more offroad orientated suspension (which is good if you'll be doin alot of offroad stuff, less good for your kidneys on the tar). But thats just my opinion, I've only had my DRZ for 2 weeks now

Edit:
As far as parts are concerned I suppose it depends, but body parts are cheap. Basic motox style plastics, easy to replace.
Gearing for the E model is really short sprocketed, I've only done 107km/h top, but as DD said, enough power for 160km/h gearing. The front suspension is amazing IMO, think it has 14 setting damping and 18 setting rebound. I'm actually too scared to adjust it