Also if i may point out something interesting, how you fare in MBBS professional examinations has very little (if any) to do with how you'd handle the steps. I know of 2 people, both having %ages in high 60s during their MBBS, who got 86 on their step 1s. I know of another female who studied seriously for 2-3 months during internship and got a 241/99 on her step 1.
The material, although in terms of subjects and perhaps basics of the first 2 profs, is all you need to know for step 1, how to go about preparing for it is a whole different issue. The more i hear of people who did just about average on the step 1, the more i think it's got to do with test taking strategies and planning more than just "knowing the subject matter".
Oh well, different strokes for different folks. Some may want to have the step 1 out of their way quickly. But I think the whole process of getting into the US healthcare system is very long and very tiring (given that I have only just taken the first baby step). IMO, there should be no rush.