I've compared them in the past. IMHO, the DTR-2000 really isn't worth the extra money unless you really, really need its additional features:
- "Hertz" mode, in addition to the standard "Cent" and "Strobe" modes already found on the DTR-1000
- Microphone for acoustic tuning
- Built-in rack lights to illuminate any rack gear below it
- Additional tuning modes (convenient for those who don't know the names of musical notes yet

)
- Can output a reference pitch for tuning audibly
- Extra inputs
The DTR-1000 may be fairly basic in comparison, but when it comes to tuners, you rarely need more than the basics. I'd just go for the DTR-1000 if I were you (that's what I did).