None of them have answers, but I took it in untimed mode (cause I wasn't concerned about time) and took the annoying time to write down questions I wasn't sure of. Which of course was a lot. Then I looked up the answers. Time consuming, but I thought it was worth it.
I only purchased and took one of them. I figured we spend so much on q bank, why spend more money to see virtually the same score on all NBME forms. Most people say they get within a few points on all forms. I was also satisfied with my predicted score and took it only 1 week before the actual date though. I didnt see a point in taking 1 sooner when I was still learning.