My fiance is doing her traditional rotation year so I have some input, I hope

. First of all, the trad. year for DOs and the internship for MDs is NO didfferent, just the programs are different from each other. In other words, there are easier trad years at a certain program, and more difficult ones at another program. This is the same for MD internship year, in that there are easier programs and more difficult programs (see scutwork, when they say "...DO (NOT) come here for your internship...choose something more cush..." My fiance is at a place where she has 4 months of electives, and there was another trad year program that she interviewed at that had only 1, so this is why she chose where she is at now.
So, the way the trad year works is that you'll have a month of OB, and another month of peds, and another month of surgery, and another month of ortho, and another couple of months for gen med, etc....this is how you "explore" other fields, even though the same "exploration" goes on in MD prelim year for those entering certain fields like neuro, ortho, anes, or any other field that technically begins at PGY2 year. once again, THERE IS NO/LITTLE DIFFERENCE. THink about it, how can an ENTIRE profession's (i.e. DO) internship be easier or harder than anothers (i.e. MD) since patient population doesn't change, and neither does your census, or difficulty of patient pathology. By that, I mean that these things do not change because the institution is a DO institution or an MD institution, but these things DO change from program to program since if you are in the inner city (MD or DO), you will see a different subset of patients than you would see in rural settings (MD or DO), and a program may have call q3 or q4 (MD or DO). I think you know what I mean.
The interview thing is interesting, but same as well. What my fiance did was "match" the osteo match for her trad year ONLY and did the allo match for her residency. This is pretty much cut and dry, but if you are doing a joint porgram in which your internship year is at the same place as your residency, then it makes no difference since you are only applying to that 1 place. 1 thing that needs to be taken into consideration is the outcome of matching at a certain match. By that, I mean that you, the applicant, matches at EITHER the allo OR the osteo match if applying to a program where you do your internship year at the same institution. Let's say for example, you are interviewing at 2 places, 1 is DO and another is MD and the internship year and the residency is at the same hospital. If you rank the osteo program in the osteo match, and you match at that place, then you are automatuically exempt from the allo match, since you have, in essence, already signed a contract. Same applies vice versa if you matched at the allo place. The thing that complicates the lives of DO students is the time issue since the osteo match is earlier than the allo match, so the student has to make a careful decision as to rank the osteo program and do the osteo match or not since it's earlier that the allo match.
Hope this helped, even a little