It all depends on what you're looking for in terms of residency.
When I went through the match a couple years ago, I took my chances with the MD match, even though I only had interviews from a couple of the MD programs I applied to. I interviewed at DO programs that I really liked, and thought that I'd enjoy my time at, but felt I would be better served at the MD program (because it was closer to where my wife was doing residency, although, the DO programs were still in the same locality). I didn't get into either MD program, and had to scramble through the DO scramble. Fortunately, the DO program I liked the best still had internship slots open, and they were willing to convert an unused IM slot to an EM slot for me, so I ended up in the EM residency I believe I really belonged in.
I'm happier in my DO program (SJWS in Cleveland) than I would have been in one of the MD programs because my hospital is tighter knit and I'm on a first name basis with most of my consultants (including the CT surgeons and the Neurosurgeons)...nothing can replace that kind of personal level of attention because when your consultants get to know you like ours do, they trust you more and when the **** hits the fan, they'll be more likely to come help you or give you the advice you need instead of just being dinguses. My hospital is a trauma center, yet we don't have surgical residents, which allows us to get more hands on experience with traumas and procedures. I see between 18-20 patients a shift, with at least 1-2 of those in seriously critical condition, whether it's via trauma or medically critical (sepsis, etc). Plus, when I use the consultants, I tend to get a mini lecture on whatever case I call them on (we had a trauma yesterday where a guy fell off a bike and had 7 rib fx's, and a grade 4 splenic lac, and a ptx and the trauma surgeon talked to me about splenic lacs for 20 minutes over the patient while we were getting him prepped to go to surgery).
One other thing you should consider in your choice (besides your comfort level), especially in an osteopathic program, is what level of service does your hospital offer? In my area, there are about 5 DO EM programs, but not all offer a really great variety of services. One is too close to a couple level 1 trauma centers, and the good cases get siphoned to them. One has a volume of under 20K per year. 3 don't have cath labs, and 4 don't offer CABG or Neurosurg capabilities. My hospital, even though it's only 250 beds, sees 40k patients a year, has 40 Critical Care beds (20 CCU and ICU), has full CT surg and Neurosurg capabilities, and has a cath lab that does about 3k caths per year. You're better served by being at a hospital that offers the full range of services, so that if you do get that ruptured thoracic aneurysm (which I had a couple weeks ago), you can repair it there instead of having to be forced to ship out your patients because you can't handle the level of acuity. It really will allow you to have a big hospital experience with a smaller hospital feel. Nothing makes you feel more secure learning how to be an EM doc when you know your hospital can really handle what you're doing....it'll allow you to become more aggressive and treat your patients with more advanced techniques.
Allopathic programs are great and will really allow you to blossom, but if you can get into the right DO program, you'll have that same experience. In my program, the attendings really let you do your own thing, which is nice, but when you have that crashing patient, they'll be there to guide you. They let you get your comfort zone, so that you feel really comfortable taking care of that patient in septic shock or the guy who's bleeding out into his abdomen. I may only be only 2 years out from graduation, but in the past month, I've seen 4 types of shock (septic, hypovolemic, anaphylactic, and cardiogenic), seen a ruptured thoracic aneurysm, and have been allowed to manage my sickest patients with my own plan of action, which has really allowed me to grow rapidly into my skin as an EM physician. I really think I can handle most things that come my way now after a couple months in our system.
PM me if you have any more questions.