Well, first, you're overestimating the altruism and spare time of MD/DO admissions offices. Desirable MD/DO schools are going to reject >95% of their >5000 applicants. Losing one applicant who did unfamiliar postbac/SMP work has exactly no effect on anything. There are now about a dozen US med schools that reject over 10,000 of their applicants.
Second, the postbac/SMP programs at DO schools have much lower admissions standards. You can't expect an MD school, or a better DO school, to respect that a DO program didn't require you to retake a 22, for instance.
Third, you can do postbac/SMP work at an MD school and find that it makes no difference at other MD schools. And you can find those who did postbac/SMP work at a DO school and got into an MD school.
Fourth, don't overestimate what postbac/SMP work can do for you. A whole lot of MD/DO postbac/SMP grads don't get into med school at all, or not until they do additional work. Nothing you do in a postbac/SMP changes your MCAT score, and your cumulative GPAs don't move much after 4 years of undergrad. If you have GPA damage, med schools don't fall all over themselves for you, regardless of what you try to do to fix your GPA. GPA redemption is an uphill climb in a strong headwind.
Fifth, it's my understanding that UNT has a good reputation at the TX MD schools. There's little reason to leave TX for a postbac/SMP.
Outcomes depend on the overall strength of your app. Most of the general strength of your app is baked in before you start postbac/SMP work. Generally if you need an SMP or if you need academic enhancement, you're starting at a disadvantage. That disadvantage is not erased by a postbac or SMP, unless you get into one of the few programs where the host MD/DO school takes lots of its postbac/SMP students.
tl;dr: be a smart consumer.
Best of luck to you.
