Here's how I did it. I purchased the four-hour mode for both exams. I gave myself exactly an hour to complete each block (to simulate a real block), but before submitting it, I spent the remaining 3 or so hours reviewing the questions and answers. If I got a question correct, super. If I missed a question, I made sure I understood why, and then left it incorrect, so my distribution wouldn't be skewed. In the end, I was pleased with my scores, but knew they could be like 100 points better because I missed some really STUPID questions (I actually got B12 and folate sources mixed up, ouch), so it was a nice confidence boost for me.
I'm not sure I'd put too much stock in the performance profile. I think the best way to use it is to look at your weaknesses, and then understand why they were weak on that particular test. Never look at your strengths and think "looks like I know that subject pretty well". Case in point: heme/lymph and renal were weaknesses of mine on Form A, but on Form B, heme/lymph and renal were off the chart, and nutrition was a weakness. I don't think I really had a weakness in any area-- I simply realized that I missed some dumb B12/Folate Q's on Form A and then botched some vitamin biochemistry Q's on Form B. I knew why I goofed, and didn't worry about it, because I knew I wouldn't miss those on the actual exam.
Also, something interesting: as far as the bar graphs go, my overall performance as indicated by the bars was better on Form B than Form A, and yet my score was a little lower on Form B than Form A. Weird.