Unfortunately, the DRZ and bikes like it make terrible motard machines. They consistantly will get waxed by CR450Fs and YZ450Fs done up for motard. Now if you are just planning on using the DRZ or KTM for just riding on the street and not to race it competitively, you'll be ok.
I was actually considering trading my GSXR600 for one of the DR400's back in the winter. My first bike was a '94 DR125 (loved it, but it got stolen). Now if I get one, it'd be a secondary bike to the GSXR.
How'd you like riding it? Are you considering buying one?