Well I take my DAT in a month and don't know anything about Math Destroyer, so I don't know how useful my CDM experience will be for you. Personally, I like CDM. I have their Royal Flush version, so I get 25 practice exams. They're all timed, 45 minutes for 40 questions and have an onscreen calculator, just like the DAT. Also, at the end of the exam, it breaks everything down for you, showing your total % for each math category (i.e. trig, geometry, algebra, etc). But what I like best is that for every question, there's an explanation in both text and video form. The text explanation isn't always clear, but the video takes you through everything step by step, just like your high school math teacher would. Hope this helps and good luck!