I know one must take all NBME to get a good understanding of what your score would be like on the actual exam but, I have heard from others who have taken the exam that NBME 2 was the best predictor of there actual score. Has anyone else had a similar experience?

yeah probably, but now they have NBME 6 too...so i would just take them all online at different stages in your prep.

but i would save NBME 6 until 2 days before your actual exam just so you have the newest information for your real test.