No. If they want to submit you to a med board, do it. It is not the same as a chapter.
VA disability ratings are done during the med board. Before you leave post, you know what your %s will be & will start getting disability $ about 2 months after ETS. If you take a chapter, you're on your own to do all that & it could take over a year to get your ratings.
Second, if the condition(s) getting you med boarded come up to 30%+, you get medically retired. Even as a PFC with barely any time in. Medical retirement has its own benefits, to include VA health care for life for anything for you, and the option for Tricare for you & (future) dependents. Tricare currently costs $47.10 a month for a family. You won't find healthcare that cheap anywhere else. If you do it yourself, your VA ratings must total 50%+ to be eligible for total VA healthcare; less than that & you are only eligible for care related to your rated condition(s) & it won't meet the criteria for the required minimum coverage.