Advice on applying for MSc in IMS vs Physiology Programs

I am deciding whether I want to apply to either the MSc IMS or Physiology Program and would love to hear any insights from current grad students (pros, cons, regrets...). Also I know it is pretty late but I just recently decided that I want to the apply to these programs. Would I still be able to find a PI this late? Once you find a PI, is it pretty much guaranteed to get in as long as you meet the requirements? Any advice would be appreciated!