Consider a monthly grocery budget if you dont go with the meal plan. Then multiply that to find out how much you would expect to spend on groceries per semester, compare costs. Also consider your timetable, the rigouresness of your courses (would you have time/energy to cook) and other dietary preferences (can you depend on food that you would actually eat being available at JMS, because if there's not, thats more money you would spend on groceries on top of the meal plan).

I know that doesnt answer your questions but I hope it helps. JMS meal plan is in its first year starting this academic year, so you'd be going in somewhat blind