Night Reader -

the 800score CATs are not the best out there - but not the worst either.

At Veritas we have done a statistical analysis of these tests and found that compared to the actual GMAT the score on the 800score is generally a little higher than it would be on the actual GMAT. This is because the verbal is not as difficult as on the actual exam. With that said, I actually think the verbal can be tougher for a student who is well-prepared because the questions are not written as well and proper GMAT verbal techniques do not always work.

As to the predictive nature of the test, I would trust the score given by the 800score test even a little less than other non-official tests. My tutoring students who take these can be way above or way below what the score should be. That said, they are worth doing if you treat then the same way you do other non-official practice tests. You are really working on doing problems on the computer and your timing, stamina, etc. Do not use these as a benchmark of your potential test day score.

That's my experience with these. Good luck!