Having done some EMS volunteering myself, I will say it is nice on its own. I mean driving an ambulance with lights and sirens on the opposite side of the road is thrilling but beyond that for the purpose of leveraging EMS work to becoming a doctor, I would say they are not related at all. As an EMT, you are packing the patient off and transporting them. If you think an EMT-B will gain so much knowledge from the semester course that they will be bringing people back from the dead, you are utterly mistaken. There were so many people in my class who had no idea what they were doing and they were still getting certified. I left EMS volunteering after about a year because I was working with way too many incompetent people and I the experience just was not as stimulating as I thought it would be. It had its moment but it was a fleeting one at that.
So with EMS work, do it IF YOU LIKE IT but don't think you're going to be getting some top-rate experience that will somehow make you a better doctor. Seeing and doing are too totally different things and that applies to any type of shadowing. With EMS work, there is a lot of seeing but the doing is done by those who you are handing the patient off too and you RARELY get to see that.
Scribing is the better of the two but its still an observatory activity with zero continuity. It's like sitting in the jump seat of a 747. You can hear the pilots talk about all the jargon but no way in hell would you let that jump seat passenger grab the controls based on how much jargon they know.
I've said this before and I will reiterate it again. Getting an acceptance letter is going to be based on paper data. Beyond that, you just have to demonstrate that you have some clinical exposure to the field of medicine and that you understand what you are getting into. You do not need activity after activity of clinically-related experience to impress an adcom. More clinical experience does not equate to any type of diagnosing capability or ability to treat. You haven't gone to medical school yet remember.
Pick one or two shadowing activities and do some GENUINE volunteer work to demonstrate empathy and commitment and I think you will have that part of your application covered. Adcoms are not stupid, they know getting good grades takes up a significant amount of your time.
In one of my older posts, I said our program values "commitment," "dedication," "passion," and "demonstrated excellence." Most people at this school have demonstrated all of those qualities with activities that are many times NOT clinically related.