I thought I'd chime in because I found the discussion interesting.
I think the difference between FM and Peds is that when you pick FM, you make a commitment to primary care and taking care of people out in the community. I think that's the first and foremost difference and I think training reflects that. Pediatric training in FM residencies vary signficantly, mainly because communities vary significantly. Some programs will send FM residents to tertiary children's hospital for their inpatient services either working directly with an attending or with a pediatric residency team. Some programs (like the one I trained at) has its own pediatric service and pediatric floor in the community hospital. So, if you're evaluating the pediatric curriculum at FM residencies, that's something you need to look into.
It's true that in FM residencies, the curriculum exposes you to fewer months of pediatrics compared to a pediatric residency. That goes without saying. The one component to not discount is the continuity clinic component in FM residencies. FM residents spend increasing number of half-days in their own continuity clinic (ranging to 3-5 half-days in their own clinic), so a lot of general pediatric training occurs in the clinic if there so happens to be a big peds practice in the clinic and that component may not be immediately obvious when you gleam the FM block curriculum. Continuity clinic experience is interwoven through all 3 years. At my old program, residents felt adequately trained for outpatient pediatric medicine, because we spent 3 years doing it (in addition to the block rotations).
Making a commitment to primary care when you pick FM is, I think, an important point. Since many FM programs train out in the community, the training may underexpose the residents to a lot of the tertiary care needs (critical care, neurosurgery, surgical, etc) that pediatric residents would get. I don't feel too-too bad about it. In my community, many general pediatricians don't admit their own hospitalized kids (and instead admit to our pediatric hospitalist service whom the FM residents rotate through and take call for). And, in my community, it's nearly impossible to get pediatric subspecialist back up in the general acute hospitals. So, absent a PICU, we often times ship out our crashing kids after we stabilize them to the downtown univerisity hospital. So, I feel that my training is appropriate for what capabilities my hospital provides (5-10 beds for inpatient peds). Newborns are a different story. I have lots of back up for newborns at my hospital and get into the call rotation to take care of normal newborns. I have in-house neonatologists who back me up.
Regarding Ob/Gyn, I felt that learning obstetrics and prenatal care and maternity care helped me learn pediatrics better. I don't think the obstetric portion is necessarily the key differentiating point. Rather, I think the gynecology portion is more important part if you're in primary care and thought I had good training in that. And, having rotations dedicated to OB/Gyn gave me the relationship with the attendings that if I have a question about an outpatient gyn issue in a kid, I felt that I could ask the Ob/Gyn attending for advice if needed.
Now that I'm out, hospital wise, I admit my own kids for general pediatric issues (asthma, pyelo, appy, pneumonia, fever r/o sepsis, meningitis). I do my own LP's if the ED hasn't done them when they call me. I take newborns. If I have a kid who's requires more capability than the hospital can provide, I ship them out to the university. Outpatient wise, I see 20% pediatrics, 30% if you consider "older" kids, and 50% if you consider young adults. I work urgent care and have open slots for acutes and always work in someone who needs help right away (sutures, IV's, X-rays, fracture management).
Businesswise, I think my peds numbers is just about right. I like seeing kids, but picked FM because I didn't want to do it all the time. I think my peds numbers reflect the general population in my community, where there are more adults who need me than there are kids who need me; which helps my income. I don't feel that I compete that much with pediatricians because I take Medicaid and many pediatricians in my community have stopped taking care of these kids. Most of the private insurance kids I pick up are the ones who come to me because I also see their parents or older siblings, who've tagged on to me because I manage their urgent care/acute issues. I get a lot of school-age kids and up when kids feel like they've outgrown their previous pediatrician.
I think the one sore spot that I feel like I'm deficient on is the care of syndromic kids. In FM training, especially out in the community, you don't get to manage too many of these kids. And for the few I have, I have specialists on board. I will say that I see a lot of syndromic young-adults who've fallen off their pediatricians. I feel like I'm filling a gap/need in my community, because no one else will take care of these guys.
The other gap in my training is the acutely decompensating kid. I can manage the ventilator in the first 24 hours for an adult, but am less skilled in doing that for a kid/neonate in the first 24 hours. This is an artifact of the hospital I trained at. We didn't have a PICU out in the community. If this skill is what's called for in the community you want to practice in, either train in pediatrics or pick a resource-limited FM residency program (rural/county) where you get training/practice to those skills.
I think if you want to be a pediatric hospitalist, it's probably best to go through pediatrics or med-peds. Most med-peds programs are very inpatient oriented and very tertiary care oriented. And the thought of taking 2 boards to do primary care and keeping up with double the number of CME hours was unappetizing for me. For the amount of primary care physicians and lack of specialists out in the community as my community, I would've expected more med-peds trained physicians... but there isn't, and I don't know why.
I think if you're interested in outpatient primary care, I think FM training in peds may be sufficient. The decision really rests with whether or not you want to also take care of older patients and/or your patient's family members as well. The one advise I will give you is that if you do pick pediatrics with an interest in outpatient primary care, make sure you pick up lots of Gyn, ENT, Ortho, Sports Med, Uro, and Ophtho training and get lots of practice doing outpatient procedures (toenails, sutures, IV's, circs). These rotations/procedures are built into the FM curriculum that may not be built into a Gen Peds curriculum and are issues that come up all the time in outpatient clinics.