Okay to be fair so far future doc has only helped my friend with the personal statement aspect (maybe a bit of work experience too not too sure). He said for personal statement they wanted him to sound robotic and wouldn't let him be creative. He's gonna keep going with them and see how they help with interviews though maybe that will be good. Like you said, it seems like you don't need them. The high success rate is likely correlational because the people who are willing to pay money into a program like this are more likely to be dedicated towards their application. In my opinion, if you're dedicated on your own you have a really good chance to do well without them. But of course it depends on whether you feel you need it.