I'm a graduate of an MSTP and now a senior EM resident. My residency does have a strong research program (at least as EM goes). In the interest of full disclosure, although I am going into academics I no longer plan on research being a major component of my career (completely a personal decision, no reflection on my MSTP or residency program).
I agree with Q that there are some challenges to being a physician-scientist in EM that aren't encountered in many other specialties. However, it is possible with work and I think there are some positives that MD/PhDs should consider as well.
Although basic research is rare in EM, I think there are terrific opportunities for translational research. The major areas of interest currently are in critical care and resuscitation, but the relative paucity of established investigators makes carving out a unique niche easier.
Clinical research is the larger area of EM research currently. EM is huge on clinical decision rules and there are several well-established groups running multiple large clinical trials. Note, however, that this kind of research is not what the typical MD/PhD has much experience in.
It is certainly recognized that there is not enough high-quality research going in EM, and there are efforts to change this. Within the last few years the NIH established the
Office of Emergency Care Research to help coordinate research in EM (one disadvantage that I hadn't mentioned was funding, as EM research often doesn't fit well into one of the NIH institutes). In addition, there are EM programs with research fellowships (my program has one, for example).
The flexibility of shift work in EM has its advantages too, since as you get funded it's fairly easy to buy down your number of shifts. The established investigators at my program have 50% or less of their time being clinical. On the other side of the coin, EM of course involves nights and weekends and unless yo are very senior you will be expected to do your share.
There does anecdotally seem to be more interest in EM among MD/PhDs, although I'm not sure this is separate from the general increasing interest in EM. Prior to 2010, my MSTP had only had one student match in EM in their 20+ year history, and now matches one about every other year.
I'm happy to answer any questions I can.