The "S" in SMP is special. There's nothing special about a 1-2 year terminal masters, with respect to increasing your chances of getting into a US MD school, unless the program puts you through most/lots of the first year of med school as an audition for med school. Again, there are about 15 programs that put you through med school coursework. There are hundreds that don't.
Med schools are familiar with SMPs. Med schools will NOT take the time to research a program that offers a 1-2 year terminal masters. They are not curious about the rigor of some new program that doesn't include med school coursework. It's just a terminal masters. It might be rigorous. Success in the program might be a true sign of your true academic prowess for med school despite a poor undergrad showing. But med schools aren't going to go find out if that's true. They don't care about your grad work unless you got reviewed respectable pubs out of it. Terminal masters programs aren't pub-generating. A library thesis isn't a reviewed reputable pub. Med schools have to reject 90% of their applicants. They aren't looking for things to be all "oh look how interesting this student's masters program is" because every app in the pile has something they should go look at. They don't go look. ~5000+ apps per med school. ~150 seats per school.
As I said six years ago (yikes) in my categorization of GPA enhancement programs, a terminal masters isn't necessarily a bad idea. It's just a bad idea if you think it's going to change the perception of a poor undergrad performance. A terminal masters program is selling you a product. If the webpage tells you it'll help you enhance your record for med school, that's marketing. It might be true. If the program is completely wide open about where its grads are now (Cincy, Mississippi are nice examples of this) then you know for sure. Usually you don't.
If you have a poor undergrad record, you're not supposed to want to go to med school. You won't find a nice tidy product to buy that makes it all okay unless you're eligible for Temple or Tulane ACP, and then you'd seriously better be ready to work. GPA redemption is a hot mess. Successfully finishing an SMP at a US MD school might still "just" get you into a DO school. Hot expensive risky mess. Why? Because >55% of US MD applicants get rejected every year. No adcom is excited to see one more low GPA app, by default. No anonymous old fart on SDN can hand you a formula. Good lord I've tried.
Public service announcement: no program will fix a low MCAT. What you do for a low MCAT is get a good MCAT. Don't go to med school with a low MCAT even if a med school says they'll let you.