I'm a graduating MD PhD. My PhD is in retrovirology, fell in love with Psychiatry after beginning my last 2 years of clinical rotations after coming back from grad school, lured me away from Heme/Onc. I did an away rotation at Columbia, spoke to the PD there. Anecdotally, he asked his fellow PDs at high powered research programs (approx 20 programs, i.e. Yale, Hopkins, UCLA, UPitt) how many MD/PhDs they had, and a couple of years ago the number was ~30. Psych and neuroscience are becoming very hot, with behavorial genetics, epigenetics, imaging, etc. When I mentioned my concern about having a PhD in Micro/Immuno, it was not a concern as far as he was concerned. Psych is getting more MD/PhDs that may have gone to neurology or IM in the past, but its still a small number currently.
In summary, yes, you would be highly sought after for residency and in academia, and if the democrats retake congress the NIH budget should be improved. One caveat, I've seen this with some MD/PhDs, you can be a research god, but if you have zero interpersonal skills, you will not do well in Psych, or clinical anything for that matter. And with Psych, you have some of the least popular patient populations, so think about it first.
My 2 cents,
Zen76