My Qvault scores (started doing about a test every 3 days or so 3 weeks before test day) were something like: 17, 17, 18, 21, 20, 19, 20. Moral of the story, I averaged about a 20. On the real deal made a 22 on bio. You have to keep in mind I did tons with cliffs and barrons, and did the destroyer bio questions at least twice so it wasn't all qvault. But I was very impressed with the program and thought that out of all the resources I used, it best replicated the feel of DAT bio questions and that the scores were a decent predictor of my success.
Good luck!