Some people seem to be conflating 3rd/4th year to residency in terms of the degree that it affects your knowledge. They're not comparable. You should absolutely as a DO be trying to strive for a great residency program, and usually this means a strong ACGME program, because this will have the greatest impact on how you practice.
Also, I know some DO schools rotate the majority of their students through horribly small places, but that is not the case across the board. I never rotated on the inpatient side of a hospital that was smaller than 250 beds, and I did multiple rotations at systems with 500-600 beds. It really varies both from school to school and even student to student.
I was told by a peds PD he finds that MDs that come in have a little better handle on the knowledge base portion, but that the DOs are much more comfortable talking to and dealing with patients. Could be an anomaly but that was his take. Said after a year there is very little to no difference between the two.
Most people I've talked to have said something similar in terms of everyone being the same by the middle or end of intern year, if they even see a difference in the beginning at all.
Peds is a field that I feel is likely heavily affected by whether or not you attended a good school with rotations through a Children's hospital. A lot of DO schools don't, and most regular hospitals simply don't have the peds volume to support the level of learning you'd get at a Children's hospital. It's more a product of the way the field of peds has changed over the years (i.e. significantly less admissions for "regular" illness and less sick kids thanks to vaccinations) than anything else. Because if that you'll see very different things in a Children's than you will on your core peds rotation at the majority of DO schools.
I think there are a couple different fields that are affected more by poor exposure early on than others. FM, Psych, EM, Anesthesia, Rads, etc. are pretty much practiced similarly enough wherever you are that it's not a huge deal. Peds, most surgical programs save
maybe Ortho or General depending on where you are, and maybe OB (again depending on volume) are fields I see where going to a smaller community hospital for 3rd and 4th yr may be detrimental.
I'm also interested in seeing the link.
Given the attitude in his posts it really sounds like he's based in a DO unfriendly area.