I had a ~3.9, was valedictorian and president of the class (plus some other shtuff - B-school was a TOTAL blast). However, on the interview trail most either said, "Hmmm, that's an interesting background," or actually felt that they had to question my seriousness about pursuing an MD/PhD (as in, "So, why would a BUSINESS (sneer barely concealed) type want to go to med school?").
Again, perhaps the above is a bit of an overstatement, but I did find that the MBA was more of a curiousity and not valued all that highly by ad-coms. It certainly didn't hurt, but its value was less than the effort to get it. They liked the volunteer time in the ED and the paper from a pre-doc fellowship a WHOLE lot more.
P