Regarding the balance between surgery and lab research. As an MD/PhD student, I was always told that "surgical research sucks" (usually in those exact terms, but with a knowing look that precluded any need to discuss further.) Now that I am most of the way through postgraduate training in a traditionally MD/PhD-friendly field, pathology, I find it extremely frustrating to discover that some of the best examples of the triple threat are actually surgeons.
I admire these people a lot. Somehow we have people who balance a full OR and clinic schedule with what I would recognize as meaningful basic and translational research that they initiate. Just look at the abstract book from ASCO or AACR or see what the surgical faculty at any well-known place are doing. I am talking about tenure track faculty. Meanwhile, there is almost no one in our path department who is both running their own grant-funded lab, i.e., staying on the tenure track, and signing out surgical pathology. The typical claim is that it's just too hard and those who do take a stab at it usually don't end up flying. What the heck? Our patients are mounted on three-inch glass slides. They do not call for prescriptions or get wound infections. We do not have to round on them. Yet economics and circumstance have conspired so that the pathologist-scientist is actually rather rare, while the surgeon-scientist is not all that uncommon.
I would be interested to hear if anyone has any idea as to what specifically drives this dynamic. My own guesses are two. (a) Surgery is profitable. Thus surgical departments can throw relatively more money at their research-oriented attendings. That means less effort needed to compete for grants, although our surgical labs nonetheless all have multiple R01s. (b) Everyone in pathology is always harping on how "we have the tissue," but actually the surgeons have the patients and can also demand the tissue. I have also been told that standards to stay on the tenure track in surgical departments are just not that high, but that seems like sour grapes.
As neurotroph pointed out, as PIs surgeons can be somewhat absentee. But invariably they have very good PhD research faculty associated with their group and the result is a big happy translational research family. Again the economics are a little puzzling to me.
The point of this post is that if you are attracted to a surgical career, that is not at all incompatible with the ideals of the MD/PhD pathway. Caveats for this post include that I know surgeons are not a monolithic block, nor are their specialties, and that I am sort of ignoring all but basic science research.