Ditto.
I took my NERB last weekend, with only 1 week to screen patients. I ended up with perio 100, restorative 95. The test doesn't really test your clinical skills, because I have seen people who are as good as me, or better fail the test.
As far as modifications, I went into the exam knowing I might need one, but I just skipped it and focused on doing the preps and caring less about losing points. My class 2 prep was approved, but the examiners asked me to place a liner (I didn't request a liner). A classmate across the hallway requested 3 modifications on his class 2, and he ended up failing because the lesion got too big and caries was left behind.
If you have no problems on the exam (i.e. patient shows up, lesion is fairly ideal, no pulp exposure, no caries left behind, do the paperwork right, don't argue with examiners, etc), you will easily do very well.
Good luck