You know what, guys. So far I have never seen a perfect GMAT-CAT software out there beside PowerPrep. PowerPrep has the only problem that it repeated the questions from OG. PR software is too buggy. Kaplan scores people to low, however, its question bank is good. The explainations suck big time. Peterson's software is OK. It will let you to pause the test, a feature that you cannot find in any other software. But Peterson's has a weakness that it is too slow in some computer and the size of the software is huge, even though it contains only four tests. I didn't try 800score, but according to many people, it is as same as crack-gmat which have irrelevant questions.
I am thinking about building my own CAT to kick all of them out of business. It is just ridiculous.