Former postbacc, current MS4, future internal med resident chiming in.
The postbacc program definitely got me to where I needed to be. The classes are very, very doable provided you put in the work and don't slack off. Unless they've changed anything drastically, you will have more then enough time to study since your in class for about 3-4 hours a day. Go into the program like it's your M1 year, not a 5th year of college and whatever you do, don't fall behind! Alot of my closest friends in med school were my fellow postbacc classmates so definitely help each other out. Good luck and can't wait to meet more postbacc alums in the future!