@MarkDavidChapman: Thank you for adding to my post and making it complete.

@Simba2012: I did Grockit,
MGMAT and GmatPrep. As you said, nothing beats GMATPrep. the other tests were of similar quality and are helpful to track your improvement, however I like
MGMAT better since it provided the analysis.
@bb: thanks for your input. I am planning to apply to Darden (fewer essays), Kellogg and Chicago. I contacted Poonam@myessayreview and she is working during Christmas and new year (
e-GMAT recommendation). I am almost halfway through the core essay for Darden (1st draft only). I plan to do the schools in sequence to ensure that we dont compromise on quality.
@sandeepsharma: The number of mistakes varied by practice tests.
MGMAT tests were more tolerable to mistakes. I could get a 34 even with 12-15 mistakes. GMATPrep was not so liberal. Grockit was somewhere in between. The best I every scored on any mock was 45 (assuming you are talking about Verbal), and I made 4-5 mistakes overall in that mock. let me know if you need to know more.