They aren't nearly as different as IP makes them sound. That difference is even less pronounced for Step 2.
A lot of the knowledge is identical. They may be different exams where you have to modify your approach to the questions (primarily because they are different stylistically), but its not really different like you need to learn how to "think" about and "approach clinical situations and pathology differently". I got to be honest, when I read that post, I had to take a step back and wonder if IP had actually taken both.
You study for them the same way. Of course you learn the material, and of course you study pathology hard during 2nd year to know it, but there isn't some hidden magic to the USMLE. You either know and understand the material or you don't. The COMLEX is slightly easier in terms of how they ask questions, but the content is unpredictable and exactly what they are asking isn't nearly as clear. You don't have to approach building your knowledge base any differently. The gold standard for both for actually learning the material is still UWorld (for content in the explanations), FA, and Pathoma. Feel free to supplement however you wish, but that's still what you need.
Also, we don't need to speculate on how many DOs take the Steps.
In the 2013-2014 year there were 6636 DO matriculants (
http://www.aacom.org/docs/default-source/data-and-trends/AppEnrollGrad2012-2017.pdf?sfvrsn=24), and in 2015 there were 3222 DOs that took the USMLE Step 1 with a pass rate of 93% (compared to 94% for US MDs that year). This info can be found here:
http://www.usmle.org/performance-data/default.aspx#2015_step-1. That's 48.6% of all DO first year matriculants. Keep in mind though, that this doesn't take into account the DOs lost to attrition, so the real percentage of eligible DO test takers that take the USMLE is likely higher (probably more like 50-55%).
Keep in mind also that many DO schools, mine included, actively dissuade their students from taking the USMLE. At my school, they basically scared them off or told my classmates it wasn't necessary by frequently quoting that "70% of ACGME PDs accept the COMLEX" stat. I remember in 2nd year many people not taking it because they were convinced of that and because they didn't want to shell out another $600 for an extra exam. The majority of people regret not taking it, not the other way around.
Also, IP kind of glossed over my advice. I said if you're doing well, plan to take it. If you then take an NBME and you're well below passing, then forget it and focus on the COMLEX. If you are passing the NBME with more than 4-6 wks of dedicated study in front of you (I recommend that you take it a few mos out), chances are, you'll be able to get close to average or at least 220+ by test day. And again, you should expect to take one or two more NBMEs before the actual test, and be prepared to cancel if it looks like you won't hit that.
Also, the doom and gloom is quite overstated, but that's a discussion for another day.
