I didn't defer a year, but I did the post-bac program last year.
If you're already in med school, I wouldn't defer a year to do the NIH pre-IRTA program. Half the point of the program is to help you get into medical school. Though I learned a lot of cool stuff and had an awesome experience, I have friends who had a terrible time. It all depends which of the institutes you get accepted to work at and if you are in their clinical section or in one of the many labs.
If you want more info, feel free to PM me.