I interviewed at VCU back in '99. As I recall, they advertised getting an MD/PhD in 6.5 yr. Basically they were very specific about which labs you could work in, and they pretty much cut out MS4. When I asked about this, the Director replied that "Most of the 4th year is fluff" anyway.
I can't see how you could get done in 5yr. We've had MD/PhD students barely get done in 7yr, and some of these had previous Masters, so they got out of most grad courses. Most do 8-9 total, with the PhD taking 4-5 yr. We've also had a few outliers taking 7-10 years in the PhD part, but luckily those are few and far between!