For what it's worth, I'll just share my personal experience. I was in one of the summer classes. My sim partner and I did exactly what we were told to do throughout the process, we studied together and with a small group of people back from class at the hotel. We studied hard, but took breaks on the weekends as needed. We did our best to come in prepared for each lesson, and had questions ready for our instructors. At no point did we really feel unprepared. When we did feel like there were gaps or inconsistencies, we asked questions and made sure we understood what was expected of us. We were able to make it through with no XFT and no failures. I know of at least a few other groups who also managed to get through with no issues.
If you take the process seriously and ask for help when needed, I really see no reason why you shouldn't be successful.
I know first hand of 4 people who washed out in my class. All of which sadly seem completely legitimate. One of them was part of our study group, but unfortunately really struggled throughout the process to grasp even the most simple concepts of the 1-2-3 rule, takeoff mins, marginal, 17347 rule, etc. Let alone systems and limitations. We all tried to help him out, but he sometimes wouldn't show up to our study sessions. Another one was in our mock KV group and unfortunately was unable to answer almost any question... He was given extra training and still failed the mock KV. He was also one that didn't have a study group. Without fail, studying alone is a recipe for failure. Do yourself a favor and find yourself a good/small group of people to work with.
Everybody I know who worked hard and felt confident made it through the process. Many received XFTs but that is a non-issue. I haven't heard of anyone failing their MVs, and a few did fail LOE, but passed on the second attempt.