As a former orthopod finishing PM&R, I can pretty safely say that all sorts of surgical specialists are finding the virtues of physiatrists too valuable for it to go away any time soon. As far as having a low starting salary, it is higher than internal medicine, pedatrics, psychiatry for the most part. Furthermore, those are published salaries. Private practices, especially those with high procedure count are usually much higher. It comes down to utilization of resources. A surgeon makes money when she is in the OR. Time spent seeing non-op low back pain, neck pain, shoulder pain is time taken away from a much higher paying procedure. Most surgeons would be very happy spending 4 or 5 days a week in the OR and none in the clinic. By having a physiatrist in the practice, the algorithm flows much more efficiently. Like others have mentioned, the ads in the journals are academic surgical/specialist departments who are hiring PM&R physicians, which has a trickle down effect.
Another nice thing about PM&R is that there are enough open-minded practitioners within its ranks to keep it from being artificially bounded. There are physiatrists who do nothing but medical acupuncture and are incredibly successful. Some only do Botox or other local procedures. If you are not one who sees opportunities and are able to execute on them, perhaps PM&R has too much pioneering freedom for you.
The financial rewards of medicine is related to business acumen. Why are young physicians so concerned about "salary"? Whatever happened to "practice"? During a PM&R residency, one actually has time to bone up on private practice business law, accounting, marketing, etc. Why are physiatrists not the ones employing surgeons as technicians? I have managed to read enough business books over the past two years for an MBA, and (God-willing) plan to live on no less than my surgical counterparts. In the time I have been in residency, my stock portfolio has effectively doubled. In the past three months, I have written up my H&P/Consult/Follow-up templates for the top ten diagnosis my practice will probably see. I am now developing my billing sheets, weekly clinic design, web-page, filling out my applications for UPIN, state licensing, and other practice related documentation so that I will be paid at the end of my first month in practice. None of this will be taught to you, but you will have more time than your surgical/specialist colleagues to get a headstart.
Last but not least, PM&R practices medicine as it should: with the whole patient in mind. Physiatrists consider not only the disease, the cure, but also the social, economic, and long-term impact on patients with acute or chronic disability. It has had an unfortunate reputation of rather "lifestyle" oriented persons who are not as motivated in general. I saw things differently and have planned to use my time and my mind to create the best life possible for my patients and my family.
Best wishes to all of you with the imagination and motivation to live well, regardless of your chosen specialty.