The thing about medical school is that "it isn't over until it's over". If you struggle during the pre-clinical years, you have a shot at honors during the clinical years. Also, sometimes folks who ace the preclinical years, struggle with the clinical years. In short, there is something to challenge everyone at any time over your course of study.
That Marshall Program works best for students with learning disabilities. You need to be sure that you have a diagnosis before you enroll in this type of program. Yes, I have sent more than a few students to that program for strategies that can help them get through the rest of their education and into residency.
If you are struggling, your first stop is what is available to you at your school. Are there tutorial sessions? Do your professors have office hours? Have you had a chat with the dean to see what else may be an option for you before you head off to a program that may or may not work for you. There is not dishonor in asking for help if you find that you need it. After all, you are paying thousands for tuition and you need to get every dollar's worth of assistance that you can.
In answer to your original question, yes, students who have struggled with one aspect of medical education are perfectly capable of excelling in other aspects of their education. You just need to work out what you need, what is available to you currently and how you can utilize your resources for the best outcomes.
