If you can, get both. I felt that the real dat was a blend of the two programs. For CDR, question style, especially for tone/inference questions, was spot on. However, the passage content was far from representative. Many CDR passages were not based in science at all.
TS passages were very representative of my test. The search and destroy questions were also very similar, though they kinda followed the passage more so than the real DAT (I.e. the questions weren't randomly scattered and did not follow the passage chronologically as much as TS does).
If you take both of the positives from each program, you should be set to perform decently.